diff --git a/src/main/kotlin/io/emeraldpay/dshackle/upstream/HeadLagObserver.kt b/src/main/kotlin/io/emeraldpay/dshackle/upstream/HeadLagObserver.kt
index 7138c6b2..054c4247 100644
--- a/src/main/kotlin/io/emeraldpay/dshackle/upstream/HeadLagObserver.kt
+++ b/src/main/kotlin/io/emeraldpay/dshackle/upstream/HeadLagObserver.kt
@@ -34,7 +34,8 @@ typealias Extractor = (top: BlockContainer, curr: BlockContainer) -> DistanceExt
 abstract class HeadLagObserver(
     private val master: Head,
     private val followers: Collection<Upstream>,
-    private val distanceExtractor: Extractor
+    private val distanceExtractor: Extractor,
+    private val throttling: Duration = Duration.ofSeconds(5)
 ) : Lifecycle {
 
     private val log = LoggerFactory.getLogger(HeadLagObserver::class.java)
@@ -57,7 +58,7 @@ abstract class HeadLagObserver(
 
     fun subscription(): Flux<Unit> {
         return master.getFlux()
-            .sample(Duration.ofSeconds(5))
+            .sample(throttling)
             .flatMap(this::probeFollowers)
             .map { item ->
                 item.t2.setLag(item.t1)
diff --git a/src/test/groovy/io/emeraldpay/dshackle/upstream/HeadLagObserverSpec.groovy b/src/test/groovy/io/emeraldpay/dshackle/upstream/HeadLagObserverSpec.groovy
index 3d1f8a66..b667be41 100644
--- a/src/test/groovy/io/emeraldpay/dshackle/upstream/HeadLagObserverSpec.groovy
+++ b/src/test/groovy/io/emeraldpay/dshackle/upstream/HeadLagObserverSpec.groovy
@@ -72,7 +72,7 @@ class HeadLagObserverSpec extends Specification {
 
         HeadLagObserver observer = new TestHeadLagObserver(master, [up1, up2])
         when:
-        def act = observer.subscription().take(Duration.ofMillis(1200))
+        def act = observer.subscription().take(Duration.ofMillis(5000))
 
         then:
         StepVerifier.create(act)
@@ -111,7 +111,7 @@ class HeadLagObserverSpec extends Specification {
     class TestHeadLagObserver extends HeadLagObserver {
 
         TestHeadLagObserver(@NotNull Head master, @NotNull Collection<? extends Upstream> followers) {
-            super(master, followers, DistanceExtractor.@Companion::extractPowDistance)
+            super(master, followers, DistanceExtractor.@Companion::extractPowDistance, Duration.ofNanos(1))
         }
 
         @Override