diff --git a/cli/src/main/kotlin/com/vitorpamplona/amethyst/cli/commands/GrapeRankCommand.kt b/cli/src/main/kotlin/com/vitorpamplona/amethyst/cli/commands/GrapeRankCommand.kt
index b1c5941061..99f6294dd6 100644
--- a/cli/src/main/kotlin/com/vitorpamplona/amethyst/cli/commands/GrapeRankCommand.kt
+++ b/cli/src/main/kotlin/com/vitorpamplona/amethyst/cli/commands/GrapeRankCommand.kt
@@ -54,6 +54,7 @@ import com.vitorpamplona.quartz.nip85TrustedAssertions.users.ContactCardEvent
 import com.vitorpamplona.quartz.nip85TrustedAssertions.users.tags.RankTag
 import kotlinx.coroutines.CancellationException
 import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.asCoroutineDispatcher
 import kotlinx.coroutines.async
 import kotlinx.coroutines.awaitAll
 import kotlinx.coroutines.coroutineScope
@@ -61,6 +62,7 @@ import kotlinx.coroutines.withContext
 import java.net.InetSocketAddress
 import java.net.Socket
 import java.net.URI
+import java.util.concurrent.Executors
 import kotlin.math.roundToInt
 
 /**
@@ -129,6 +131,15 @@ object GrapeRankCommand {
 
     private const val PROBE_TIMEOUT_MS = 2000
 
+    // The probe does BLOCKING DNS + TCP connect, and dead-domain DNS lookups can hang
+    // far past the connect timeout. On the shared Dispatchers.IO those hanging lookups
+    // starve the crawl's own IO — measured +462s on the finishing drain at hop-3. Run
+    // them on a dedicated, isolated daemon pool instead so the crawl's IO is untouched.
+    private val probeDispatcher =
+        Executors
+            .newFixedThreadPool(128) { r -> Thread(r, "relay-probe").apply { isDaemon = true } }
+            .asCoroutineDispatcher()
+
     /**
      * Cheap reachability pre-probe: a raw TCP connect (one round trip) with a tight
      * timeout. Returns false only when the port won't even accept a socket — a dead
@@ -139,7 +150,7 @@ object GrapeRankCommand {
      * so an odd URL is never culled on a parse quirk — let the WS decide.
      */
     private suspend fun tcpReachable(relay: NormalizedRelayUrl): Boolean =
-        withContext(Dispatchers.IO) {
+        withContext(probeDispatcher) {
             val hostPort = relayHostPort(relay) ?: return@withContext true
             try {
                 Socket().use { it.connect(InetSocketAddress(hostPort.first, hostPort.second), PROBE_TIMEOUT_MS) }
diff --git a/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/experimental/graperank/GrapeRankDataCrawler.kt b/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/experimental/graperank/GrapeRankDataCrawler.kt
index 12dd36e1a3..db1345f0ea 100644
--- a/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/experimental/graperank/GrapeRankDataCrawler.kt
+++ b/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/experimental/graperank/GrapeRankDataCrawler.kt
@@ -1666,7 +1666,7 @@ class GrapeRankDataCrawler(
         // Concurrent TCP reachability probes in the background culler. Raw sockets are
         // cheap and short-lived; the per-relay WS limiter is unaffected (this never
         // opens a REQ), so this only bounds file descriptors during the cull.
-        private const val PROBE_CONCURRENCY = 256
+        private const val PROBE_CONCURRENCY = 128
 
         // Re-scan interval for the culler when it has probed everything learned so far
         // and is waiting for new relays to be discovered.