diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index 110c30acc..f0b51bc40 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -23,7 +23,8 @@ The following tip changes can be tested by building VictoriaMetrics components f
 
 * FEATURE: return shorter error messages to Grafana and to other clients requesting [/api/v1/query](https://docs.victoriametrics.com/keyConcepts.html#instant-query) and [/api/v1/query_range](https://docs.victoriametrics.com/keyConcepts.html#range-query) endpoints. This should simplify reading these errors by humans. The long error message with full context is still written to logs.
 * FEATURE: add the ability to fine-tune the number of points, which can be generated per each matching time series during [subquery](https://docs.victoriametrics.com/MetricsQL.html#subqueries) evaluation. This can be done with the `-search.maxPointsSubqueryPerTimeseries` command-line flag. See [this feature request](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/2922).
-* FEATURE: improve the performance for relabeling rules with commonly used regular expressions in `regex` and `if` fields such as `some_string`, `prefix.*`, `prefix.+`, `foo|bar|baz`, `.*foo.*` and `.+foo.+`.
+* FEATURE: [vmagent](https://docs.victoriametrics.com/vmagent.html): improve the performance for relabeling rules with commonly used regular expressions in `regex` and `if` fields such as `some_string`, `prefix.*`, `prefix.+`, `foo|bar|baz`, `.*foo.*` and `.+foo.+`.
+* FEATURE: [vmagent](https://docs.victoriametrics.com/vmagent.html): reduce CPU usage when discovering big number of [Kubernetes targets](https://docs.victoriametrics.com/sd_configs.html#kubernetes_sd_configs) with big number of labels and annotations.
 * FEATURE: [vmagent](https://docs.victoriametrics.com/vmagent.html): add ability to accept [multitenant](https://docs.victoriametrics.com/Cluster-VictoriaMetrics.html#multitenancy) data via OpenTSDB `/api/put` protocol at `/insert/<tenantID>/opentsdb/api/put` http endpoint if [multitenant support](https://docs.victoriametrics.com/vmagent.html#multitenancy) is enabled at `vmagent`. Thanks to @chengjianyun for [the pull request](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/3015).
 * FEATURE: [monitoring](https://docs.victoriametrics.com/#monitoring): expose `vm_hourly_series_limit_max_series`, `vm_hourly_series_limit_current_series`, `vm_daily_series_limit_max_series` and `vm_daily_series_limit_current_series` metrics when `-search.maxHourlySeries` or `-search.maxDailySeries` limits are set. This allows alerting when the number of unique series reaches the configured limits. See [these docs](https://docs.victoriametrics.com/#cardinality-limiter) for details.
 * FEATURE: [VictoriaMetrics cluster](https://docs.victoriametrics.com/Cluster-VictoriaMetrics.html): reduce the amounts of logging at `vmstorage` when `vmselect` connects/disconnects to `vmstorage`.
diff --git a/lib/promscrape/config.go b/lib/promscrape/config.go
index cbb5c654a..afd611872 100644
--- a/lib/promscrape/config.go
+++ b/lib/promscrape/config.go
@@ -11,7 +11,6 @@ import (
 	"strconv"
 	"strings"
 	"sync"
-	"sync/atomic"
 	"time"
 
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/bytesutil"
@@ -35,6 +34,7 @@ import (
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/promscrape/discovery/kubernetes"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/promscrape/discovery/openstack"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/promscrape/discovery/yandexcloud"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/promscrape/discoveryutils"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/promutils"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/proxy"
 	"github.com/VictoriaMetrics/metrics"
@@ -1330,37 +1330,11 @@ func (swc *scrapeWorkConfig) getScrapeWork(target string, extraLabels, metaLabel
 func internLabelStrings(labels []prompbmarshal.Label) {
 	for i := range labels {
 		label := &labels[i]
-		label.Name = internString(label.Name)
-		label.Value = internString(label.Value)
+		label.Name = discoveryutils.InternString(label.Name)
+		label.Value = discoveryutils.InternString(label.Value)
 	}
 }
 
-func internString(s string) string {
-	m := internStringsMap.Load().(*sync.Map)
-	if v, ok := m.Load(s); ok {
-		sp := v.(*string)
-		return *sp
-	}
-	// Make a new copy for s in order to remove references from possible bigger string s refers to.
-	sCopy := string(append([]byte{}, s...))
-	m.Store(sCopy, &sCopy)
-	n := atomic.AddUint64(&internStringsMapLen, 1)
-	if n > 100e3 {
-		atomic.StoreUint64(&internStringsMapLen, 0)
-		internStringsMap.Store(&sync.Map{})
-	}
-	return sCopy
-}
-
-var (
-	internStringsMap    atomic.Value
-	internStringsMapLen uint64
-)
-
-func init() {
-	internStringsMap.Store(&sync.Map{})
-}
-
 func getParamsFromLabels(labels []prompbmarshal.Label, paramsOrig map[string][]string) map[string][]string {
 	// See https://www.robustperception.io/life-of-a-label
 	m := make(map[string][]string)
diff --git a/lib/promscrape/config_test.go b/lib/promscrape/config_test.go
index 9455d97aa..7a728b428 100644
--- a/lib/promscrape/config_test.go
+++ b/lib/promscrape/config_test.go
@@ -17,44 +17,6 @@ import (
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/proxy"
 )
 
-func TestInternStringSerial(t *testing.T) {
-	if err := testInternString(t); err != nil {
-		t.Fatalf("unexpected error: %s", err)
-	}
-}
-
-func TestInternStringConcurrent(t *testing.T) {
-	concurrency := 5
-	resultCh := make(chan error, concurrency)
-	for i := 0; i < concurrency; i++ {
-		go func() {
-			resultCh <- testInternString(t)
-		}()
-	}
-	timer := time.NewTimer(5 * time.Second)
-	for i := 0; i < concurrency; i++ {
-		select {
-		case err := <-resultCh:
-			if err != nil {
-				t.Fatalf("unexpected error: %s", err)
-			}
-		case <-timer.C:
-			t.Fatalf("timeout")
-		}
-	}
-}
-
-func testInternString(t *testing.T) error {
-	for i := 0; i < 1000; i++ {
-		s := fmt.Sprintf("foo_%d", i)
-		s1 := internString(s)
-		if s != s1 {
-			return fmt.Errorf("unexpected string returned from internString; got %q; want %q", s1, s)
-		}
-	}
-	return nil
-}
-
 func TestMergeLabels(t *testing.T) {
 	f := func(swc *scrapeWorkConfig, target string, extraLabels, metaLabels map[string]string, resultExpected string) {
 		t.Helper()
diff --git a/lib/promscrape/discovery/consul/service_node.go b/lib/promscrape/discovery/consul/service_node.go
index ba33913ba..23f3a0003 100644
--- a/lib/promscrape/discovery/consul/service_node.go
+++ b/lib/promscrape/discovery/consul/service_node.go
@@ -94,16 +94,13 @@ func (sn *ServiceNode) appendTargetLabels(ms []map[string]string, serviceName, t
 	m["__meta_consul_tags"] = tagSeparator + strings.Join(sn.Service.Tags, tagSeparator) + tagSeparator
 
 	for k, v := range sn.Node.Meta {
-		key := discoveryutils.SanitizeLabelName(k)
-		m["__meta_consul_metadata_"+key] = v
+		m[discoveryutils.SanitizeLabelName("__meta_consul_metadata_"+k)] = v
 	}
 	for k, v := range sn.Service.Meta {
-		key := discoveryutils.SanitizeLabelName(k)
-		m["__meta_consul_service_metadata_"+key] = v
+		m[discoveryutils.SanitizeLabelName("__meta_consul_service_metadata_"+k)] = v
 	}
 	for k, v := range sn.Node.TaggedAddresses {
-		key := discoveryutils.SanitizeLabelName(k)
-		m["__meta_consul_tagged_address_"+key] = v
+		m[discoveryutils.SanitizeLabelName("__meta_consul_tagged_address_"+k)] = v
 	}
 	ms = append(ms, m)
 	return ms
diff --git a/lib/promscrape/discovery/docker/container.go b/lib/promscrape/discovery/docker/container.go
index a8ff92f8b..43444f045 100644
--- a/lib/promscrape/discovery/docker/container.go
+++ b/lib/promscrape/discovery/docker/container.go
@@ -107,7 +107,7 @@ func addCommonLabels(m map[string]string, c *container, networkLabels map[string
 	m["__meta_docker_container_name"] = c.Names[0]
 	m["__meta_docker_container_network_mode"] = c.HostConfig.NetworkMode
 	for k, v := range c.Labels {
-		m["__meta_docker_container_label_"+discoveryutils.SanitizeLabelName(k)] = v
+		m[discoveryutils.SanitizeLabelName("__meta_docker_container_label_"+k)] = v
 	}
 	for k, v := range networkLabels {
 		m[k] = v
diff --git a/lib/promscrape/discovery/docker/network.go b/lib/promscrape/discovery/docker/network.go
index 8df47e531..075fae9d7 100644
--- a/lib/promscrape/discovery/docker/network.go
+++ b/lib/promscrape/discovery/docker/network.go
@@ -53,7 +53,7 @@ func getNetworkLabelsByNetworkID(networks []network) map[string]map[string]strin
 			"__meta_docker_network_scope":    network.Scope,
 		}
 		for k, v := range network.Labels {
-			m["__meta_docker_network_label_"+discoveryutils.SanitizeLabelName(k)] = v
+			m[discoveryutils.SanitizeLabelName("__meta_docker_network_label_"+k)] = v
 		}
 		ms[network.ID] = m
 	}
diff --git a/lib/promscrape/discovery/dockerswarm/network.go b/lib/promscrape/discovery/dockerswarm/network.go
index 27bb748cb..8fe12f058 100644
--- a/lib/promscrape/discovery/dockerswarm/network.go
+++ b/lib/promscrape/discovery/dockerswarm/network.go
@@ -53,7 +53,7 @@ func getNetworkLabelsByNetworkID(networks []network) map[string]map[string]strin
 			"__meta_dockerswarm_network_scope":    network.Scope,
 		}
 		for k, v := range network.Labels {
-			m["__meta_dockerswarm_network_label_"+discoveryutils.SanitizeLabelName(k)] = v
+			m[discoveryutils.SanitizeLabelName("__meta_dockerswarm_network_label_"+k)] = v
 		}
 		ms[network.ID] = m
 	}
diff --git a/lib/promscrape/discovery/dockerswarm/nodes.go b/lib/promscrape/discovery/dockerswarm/nodes.go
index c6db715f2..592141e0f 100644
--- a/lib/promscrape/discovery/dockerswarm/nodes.go
+++ b/lib/promscrape/discovery/dockerswarm/nodes.go
@@ -80,7 +80,7 @@ func addNodeLabels(nodes []node, port int) []map[string]string {
 			"__meta_dockerswarm_node_status":                node.Status.State,
 		}
 		for k, v := range node.Spec.Labels {
-			m["__meta_dockerswarm_node_label_"+discoveryutils.SanitizeLabelName(k)] = v
+			m[discoveryutils.SanitizeLabelName("__meta_dockerswarm_node_label_"+k)] = v
 		}
 		ms = append(ms, m)
 	}
diff --git a/lib/promscrape/discovery/dockerswarm/services.go b/lib/promscrape/discovery/dockerswarm/services.go
index 5c26ad167..ac52eb3a8 100644
--- a/lib/promscrape/discovery/dockerswarm/services.go
+++ b/lib/promscrape/discovery/dockerswarm/services.go
@@ -96,7 +96,7 @@ func addServicesLabels(services []service, networksLabels map[string]map[string]
 			"__meta_dockerswarm_service_updating_status":         service.UpdateStatus.State,
 		}
 		for k, v := range service.Spec.Labels {
-			commonLabels["__meta_dockerswarm_service_label_"+discoveryutils.SanitizeLabelName(k)] = v
+			commonLabels[discoveryutils.SanitizeLabelName("__meta_dockerswarm_service_label_"+k)] = v
 		}
 		for _, vip := range service.Endpoint.VirtualIPs {
 			// skip services without virtual address.
diff --git a/lib/promscrape/discovery/dockerswarm/tasks.go b/lib/promscrape/discovery/dockerswarm/tasks.go
index d58953763..9e17825ee 100644
--- a/lib/promscrape/discovery/dockerswarm/tasks.go
+++ b/lib/promscrape/discovery/dockerswarm/tasks.go
@@ -87,7 +87,7 @@ func addTasksLabels(tasks []task, nodesLabels, servicesLabels []map[string]strin
 			"__meta_dockerswarm_task_state":         task.Status.State,
 		}
 		for k, v := range task.Spec.ContainerSpec.Labels {
-			commonLabels["__meta_dockerswarm_container_label_"+discoveryutils.SanitizeLabelName(k)] = v
+			commonLabels[discoveryutils.SanitizeLabelName("__meta_dockerswarm_container_label_"+k)] = v
 		}
 		var svcPorts []portConfig
 		for i, v := range services {
diff --git a/lib/promscrape/discovery/ec2/instance.go b/lib/promscrape/discovery/ec2/instance.go
index c111aaf30..9cacb2506 100644
--- a/lib/promscrape/discovery/ec2/instance.go
+++ b/lib/promscrape/discovery/ec2/instance.go
@@ -186,8 +186,7 @@ func (inst *Instance) appendTargetLabels(ms []map[string]string, ownerID string,
 		if len(t.Key) == 0 || len(t.Value) == 0 {
 			continue
 		}
-		name := discoveryutils.SanitizeLabelName(t.Key)
-		m["__meta_ec2_tag_"+name] = t.Value
+		m[discoveryutils.SanitizeLabelName("__meta_ec2_tag_"+t.Key)] = t.Value
 	}
 	ms = append(ms, m)
 	return ms
diff --git a/lib/promscrape/discovery/eureka/eureka.go b/lib/promscrape/discovery/eureka/eureka.go
index 86a372259..f2390f6d4 100644
--- a/lib/promscrape/discovery/eureka/eureka.go
+++ b/lib/promscrape/discovery/eureka/eureka.go
@@ -139,11 +139,11 @@ func addInstanceLabels(apps *applications) []map[string]string {
 			if len(instance.DataCenterInfo.Name) > 0 {
 				m["__meta_eureka_app_instance_datacenterinfo_name"] = instance.DataCenterInfo.Name
 				for _, tag := range instance.DataCenterInfo.Metadata.Items {
-					m["__meta_eureka_app_instance_datacenterinfo_metadata_"+discoveryutils.SanitizeLabelName(tag.XMLName.Local)] = tag.Content
+					m[discoveryutils.SanitizeLabelName("__meta_eureka_app_instance_datacenterinfo_metadata_"+tag.XMLName.Local)] = tag.Content
 				}
 			}
 			for _, tag := range instance.Metadata.Items {
-				m["__meta_eureka_app_instance_metadata_"+discoveryutils.SanitizeLabelName(tag.XMLName.Local)] = tag.Content
+				m[discoveryutils.SanitizeLabelName("__meta_eureka_app_instance_metadata_"+tag.XMLName.Local)] = tag.Content
 			}
 			ms = append(ms, m)
 		}
diff --git a/lib/promscrape/discovery/gce/instance.go b/lib/promscrape/discovery/gce/instance.go
index 65ad7bdd7..2c16a9c37 100644
--- a/lib/promscrape/discovery/gce/instance.go
+++ b/lib/promscrape/discovery/gce/instance.go
@@ -150,8 +150,7 @@ func (inst *Instance) appendTargetLabels(ms []map[string]string, project, tagSep
 		"__meta_gce_zone":            inst.Zone,
 	}
 	for _, iface := range inst.NetworkInterfaces {
-		ifaceName := discoveryutils.SanitizeLabelName(iface.Name)
-		m["__meta_gce_interface_ipv4_"+ifaceName] = iface.NetworkIP
+		m[discoveryutils.SanitizeLabelName("__meta_gce_interface_ipv4_"+iface.Name)] = iface.NetworkIP
 	}
 	if len(inst.Tags.Items) > 0 {
 		// We surround the separated list with the separator as well. This way regular expressions
@@ -159,12 +158,10 @@ func (inst *Instance) appendTargetLabels(ms []map[string]string, project, tagSep
 		m["__meta_gce_tags"] = tagSeparator + strings.Join(inst.Tags.Items, tagSeparator) + tagSeparator
 	}
 	for _, item := range inst.Metadata.Items {
-		key := discoveryutils.SanitizeLabelName(item.Key)
-		m["__meta_gce_metadata_"+key] = item.Value
+		m[discoveryutils.SanitizeLabelName("__meta_gce_metadata_"+item.Key)] = item.Value
 	}
 	for _, label := range inst.Labels {
-		name := discoveryutils.SanitizeLabelName(label.Name)
-		m["__meta_gce_label_"+name] = label.Value
+		m[discoveryutils.SanitizeLabelName("__meta_gce_label_"+label.Name)] = label.Value
 	}
 	if len(iface.AccessConfigs) > 0 {
 		ac := iface.AccessConfigs[0]
diff --git a/lib/promscrape/discovery/kubernetes/common_types.go b/lib/promscrape/discovery/kubernetes/common_types.go
index be93bbb4a..c2479ca19 100644
--- a/lib/promscrape/discovery/kubernetes/common_types.go
+++ b/lib/promscrape/discovery/kubernetes/common_types.go
@@ -28,14 +28,12 @@ type ListMeta struct {
 
 func (om *ObjectMeta) registerLabelsAndAnnotations(prefix string, m map[string]string) {
 	for _, lb := range om.Labels {
-		ln := discoveryutils.SanitizeLabelName(lb.Name)
-		m[prefix+"_label_"+ln] = lb.Value
-		m[prefix+"_labelpresent_"+ln] = "true"
+		m[discoveryutils.SanitizeLabelName(prefix+"_label_"+lb.Name)] = lb.Value
+		m[discoveryutils.SanitizeLabelName(prefix+"_labelpresent_"+lb.Name)] = "true"
 	}
 	for _, a := range om.Annotations {
-		an := discoveryutils.SanitizeLabelName(a.Name)
-		m[prefix+"_annotation_"+an] = a.Value
-		m[prefix+"_annotationpresent_"+an] = "true"
+		m[discoveryutils.SanitizeLabelName(prefix+"_annotation_"+a.Name)] = a.Value
+		m[discoveryutils.SanitizeLabelName(prefix+"_annotationpresent_"+a.Name)] = "true"
 	}
 }
 
diff --git a/lib/promscrape/discovery/kubernetes/endpointslice.go b/lib/promscrape/discovery/kubernetes/endpointslice.go
index f4a2a07ac..8e376865c 100644
--- a/lib/promscrape/discovery/kubernetes/endpointslice.go
+++ b/lib/promscrape/discovery/kubernetes/endpointslice.go
@@ -151,8 +151,8 @@ func getEndpointSliceLabels(eps *EndpointSlice, addr string, ea Endpoint, epp En
 		m["__meta_kubernetes_endpointslice_endpoint_hostname"] = ea.Hostname
 	}
 	for k, v := range ea.Topology {
-		m["__meta_kubernetes_endpointslice_endpoint_topology_"+discoveryutils.SanitizeLabelName(k)] = v
-		m["__meta_kubernetes_endpointslice_endpoint_topology_present_"+discoveryutils.SanitizeLabelName(k)] = "true"
+		m[discoveryutils.SanitizeLabelName("__meta_kubernetes_endpointslice_endpoint_topology_"+k)] = v
+		m[discoveryutils.SanitizeLabelName("__meta_kubernetes_endpointslice_endpoint_topology_present_"+k)] = "true"
 	}
 	return m
 }
diff --git a/lib/promscrape/discovery/kubernetes/node.go b/lib/promscrape/discovery/kubernetes/node.go
index 2f9605bf3..812c7f301 100644
--- a/lib/promscrape/discovery/kubernetes/node.go
+++ b/lib/promscrape/discovery/kubernetes/node.go
@@ -104,8 +104,7 @@ func (n *Node) getTargetLabels(gw *groupWatcher) []map[string]string {
 			continue
 		}
 		addrTypesUsed[a.Type] = true
-		ln := discoveryutils.SanitizeLabelName(a.Type)
-		m["__meta_kubernetes_node_address_"+ln] = a.Address
+		m[discoveryutils.SanitizeLabelName("__meta_kubernetes_node_address_"+a.Type)] = a.Address
 	}
 	return []map[string]string{m}
 }
diff --git a/lib/promscrape/discovery/openstack/instance.go b/lib/promscrape/discovery/openstack/instance.go
index 0d020b6a0..5f628d420 100644
--- a/lib/promscrape/discovery/openstack/instance.go
+++ b/lib/promscrape/discovery/openstack/instance.go
@@ -57,7 +57,7 @@ func addInstanceLabels(servers []server, port int) []map[string]string {
 			"__meta_openstack_instance_flavor": server.Flavor.ID,
 		}
 		for k, v := range server.Metadata {
-			m["__meta_openstack_tag_"+discoveryutils.SanitizeLabelName(k)] = v
+			m[discoveryutils.SanitizeLabelName("__meta_openstack_tag_"+k)] = v
 		}
 		// Traverse server.Addresses in alphabetical order of pool name
 		// in order to return targets in deterministic order.
diff --git a/lib/promscrape/discovery/yandexcloud/instance.go b/lib/promscrape/discovery/yandexcloud/instance.go
index a887745aa..f78036596 100644
--- a/lib/promscrape/discovery/yandexcloud/instance.go
+++ b/lib/promscrape/discovery/yandexcloud/instance.go
@@ -51,7 +51,7 @@ func addInstanceLabels(instances []instance) []map[string]string {
 			"__meta_yandexcloud_folder_id":                        server.FolderID,
 		}
 		for k, v := range server.Labels {
-			m["__meta_yandexcloud_instance_label_"+discoveryutils.SanitizeLabelName(k)] = v
+			m[discoveryutils.SanitizeLabelName("__meta_yandexcloud_instance_label_"+k)] = v
 		}
 
 		for _, ni := range server.NetworkInterfaces {
diff --git a/lib/promscrape/discoveryutils/internstring.go b/lib/promscrape/discoveryutils/internstring.go
new file mode 100644
index 000000000..42f429d96
--- /dev/null
+++ b/lib/promscrape/discoveryutils/internstring.go
@@ -0,0 +1,35 @@
+package discoveryutils
+
+import (
+	"sync"
+	"sync/atomic"
+)
+
+// InternString returns interned s.
+//
+// This may be needed for reducing the amounts of allocated memory.
+func InternString(s string) string {
+	m := internStringsMap.Load().(*sync.Map)
+	if v, ok := m.Load(s); ok {
+		sp := v.(*string)
+		return *sp
+	}
+	// Make a new copy for s in order to remove references from possible bigger string s refers to.
+	sCopy := string(append([]byte{}, s...))
+	m.Store(sCopy, &sCopy)
+	n := atomic.AddUint64(&internStringsMapLen, 1)
+	if n > 100e3 {
+		atomic.StoreUint64(&internStringsMapLen, 0)
+		internStringsMap.Store(&sync.Map{})
+	}
+	return sCopy
+}
+
+var (
+	internStringsMap    atomic.Value
+	internStringsMapLen uint64
+)
+
+func init() {
+	internStringsMap.Store(&sync.Map{})
+}
diff --git a/lib/promscrape/discoveryutils/internstring_test.go b/lib/promscrape/discoveryutils/internstring_test.go
new file mode 100644
index 000000000..9a4b72c3b
--- /dev/null
+++ b/lib/promscrape/discoveryutils/internstring_test.go
@@ -0,0 +1,45 @@
+package discoveryutils
+
+import (
+	"fmt"
+	"testing"
+	"time"
+)
+
+func TestInternStringSerial(t *testing.T) {
+	if err := testInternString(t); err != nil {
+		t.Fatalf("unexpected error: %s", err)
+	}
+}
+
+func TestInternStringConcurrent(t *testing.T) {
+	concurrency := 5
+	resultCh := make(chan error, concurrency)
+	for i := 0; i < concurrency; i++ {
+		go func() {
+			resultCh <- testInternString(t)
+		}()
+	}
+	timer := time.NewTimer(5 * time.Second)
+	for i := 0; i < concurrency; i++ {
+		select {
+		case err := <-resultCh:
+			if err != nil {
+				t.Fatalf("unexpected error: %s", err)
+			}
+		case <-timer.C:
+			t.Fatalf("timeout")
+		}
+	}
+}
+
+func testInternString(t *testing.T) error {
+	for i := 0; i < 1000; i++ {
+		s := fmt.Sprintf("foo_%d", i)
+		s1 := InternString(s)
+		if s != s1 {
+			return fmt.Errorf("unexpected string returned from internString; got %q; want %q", s1, s)
+		}
+	}
+	return nil
+}
diff --git a/lib/promscrape/config_timing_test.go b/lib/promscrape/discoveryutils/internstring_timing_test.go
similarity index 88%
rename from lib/promscrape/config_timing_test.go
rename to lib/promscrape/discoveryutils/internstring_timing_test.go
index a4c38aef8..18877c9a9 100644
--- a/lib/promscrape/config_timing_test.go
+++ b/lib/promscrape/discoveryutils/internstring_timing_test.go
@@ -1,4 +1,4 @@
-package promscrape
+package discoveryutils
 
 import (
 	"fmt"
@@ -15,7 +15,7 @@ func BenchmarkInternString(b *testing.B) {
 	b.RunParallel(func(pb *testing.PB) {
 		for pb.Next() {
 			for _, s := range a {
-				sResult := internString(s)
+				sResult := InternString(s)
 				if sResult != s {
 					panic(fmt.Sprintf("unexpected string obtained; got %q; want %q", sResult, s))
 				}
diff --git a/lib/promscrape/discoveryutils/utils.go b/lib/promscrape/discoveryutils/utils.go
index cd0d103c9..274933cf7 100644
--- a/lib/promscrape/discoveryutils/utils.go
+++ b/lib/promscrape/discoveryutils/utils.go
@@ -6,6 +6,8 @@ import (
 	"regexp"
 	"sort"
 	"strconv"
+	"sync"
+	"sync/atomic"
 
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
 )
@@ -15,13 +17,39 @@ import (
 //
 // This has been copied from Prometheus sources at util/strutil/strconv.go
 func SanitizeLabelName(name string) string {
-	return invalidLabelCharRE.ReplaceAllString(name, "_")
+	m := sanitizedLabelNames.Load().(*sync.Map)
+	v, ok := m.Load(name)
+	if ok {
+		// Fast path - the sanitized label name is found in the cache.
+		sp := v.(*string)
+		return *sp
+	}
+	// Slow path - sanitize name and store it in the cache.
+	sanitizedName := invalidLabelCharRE.ReplaceAllString(name, "_")
+	// Make a copy of name in order to limit memory usage to the name length,
+	// since the name may point to bigger string.
+	s := string(append([]byte{}, name...))
+	sp := &sanitizedName
+	m.Store(s, sp)
+	n := atomic.AddUint64(&sanitizedLabelNamesLen, 1)
+	if n > 100e3 {
+		atomic.StoreUint64(&sanitizedLabelNamesLen, 0)
+		sanitizedLabelNames.Store(&sync.Map{})
+	}
+	return sanitizedName
 }
 
 var (
+	sanitizedLabelNames    atomic.Value
+	sanitizedLabelNamesLen uint64
+
 	invalidLabelCharRE = regexp.MustCompile(`[^a-zA-Z0-9_]`)
 )
 
+func init() {
+	sanitizedLabelNames.Store(&sync.Map{})
+}
+
 // JoinHostPort returns host:port.
 //
 // Host may be dns name, ipv4 or ipv6 address.
diff --git a/lib/promscrape/discoveryutils/utils_test.go b/lib/promscrape/discoveryutils/utils_test.go
new file mode 100644
index 000000000..21bf3100a
--- /dev/null
+++ b/lib/promscrape/discoveryutils/utils_test.go
@@ -0,0 +1,56 @@
+package discoveryutils
+
+import (
+	"fmt"
+	"testing"
+	"time"
+)
+
+func TestSanitizeLabelNameSerial(t *testing.T) {
+	if err := testSanitizeLabelName(); err != nil {
+		t.Fatalf("unexpected error: %s", err)
+	}
+}
+
+func TestSanitizeLabelNameParallel(t *testing.T) {
+	goroutines := 5
+	ch := make(chan error, goroutines)
+	for i := 0; i < goroutines; i++ {
+		go func() {
+			ch <- testSanitizeLabelName()
+		}()
+	}
+	tch := time.After(5 * time.Second)
+	for i := 0; i < goroutines; i++ {
+		select {
+		case <-tch:
+			t.Fatalf("timeout!")
+		case err := <-ch:
+			if err != nil {
+				t.Fatalf("unexpected error: %s", err)
+			}
+		}
+	}
+}
+
+func testSanitizeLabelName() error {
+	f := func(name, expectedSanitizedName string) error {
+		for i := 0; i < 5; i++ {
+			sanitizedName := SanitizeLabelName(name)
+			if sanitizedName != expectedSanitizedName {
+				return fmt.Errorf("unexpected sanitized label name %q; got %q; want %q", name, sanitizedName, expectedSanitizedName)
+			}
+		}
+		return nil
+	}
+	if err := f("", ""); err != nil {
+		return err
+	}
+	if err := f("foo", "foo"); err != nil {
+		return err
+	}
+	if err := f("foo-bar/baz", "foo_bar_baz"); err != nil {
+		return err
+	}
+	return nil
+}
diff --git a/lib/promscrape/discoveryutils/utils_timing_test.go b/lib/promscrape/discoveryutils/utils_timing_test.go
new file mode 100644
index 000000000..f128cf2b7
--- /dev/null
+++ b/lib/promscrape/discoveryutils/utils_timing_test.go
@@ -0,0 +1,21 @@
+package discoveryutils
+
+import (
+	"fmt"
+	"testing"
+)
+
+func BenchmarkSanitizeLabelName(b *testing.B) {
+	labelName := "foo-bar/baz/aaaa+bbb"
+	expectedLabelNameSanitized := "foo_bar_baz_aaaa_bbb"
+	b.SetBytes(1)
+	b.ReportAllocs()
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			labelNameSanitized := SanitizeLabelName(labelName)
+			if labelNameSanitized != expectedLabelNameSanitized {
+				panic(fmt.Errorf("unexpected sanitized label name; got %q; want %q", labelNameSanitized, expectedLabelNameSanitized))
+			}
+		}
+	})
+}