diff --git a/internal/verifier/recheck.go b/internal/verifier/recheck.go
index ebb46a24..e048a6fe 100644
--- a/internal/verifier/recheck.go
+++ b/internal/verifier/recheck.go
@@ -113,17 +113,23 @@ func (verifier *Verifier) insertRecheckDocs(
 	verifier.mux.RLock()
 	defer verifier.mux.RUnlock()
 
-	dbNames, collNames, rawDocIDs, dataSizes := deduplicateRechecks(
+	start := time.Now()
+	dbNames, collNames, documentIDs, dataSizes = deduplicateRechecks(
 		dbNames,
 		collNames,
 		documentIDs,
 		dataSizes,
 	)
+	fmt.Printf("----- deduplicate time: %s\n", time.Since(start))
 
 	generation, _ := verifier.getGenerationWhileLocked()
 
 	eg, groupCtx := contextplus.ErrGroup(ctx)
 
+	// MongoDB’s Go driver starts failing requests if we try to exceed
+	// its connection pool’s size. To avoid that, we limit our concurrency.
+	eg.SetLimit(100)
+
 	genCollection := verifier.getRecheckQueueCollection(generation)
 
 	sendRechecks := func(rechecks []bson.Raw) {
@@ -175,7 +181,7 @@ func (verifier *Verifier) insertRecheckDocs(
 			PrimaryKey: RecheckPrimaryKey{
 				SrcDatabaseName:   dbName,
 				SrcCollectionName: collNames[i],
-				DocumentID:        rawDocIDs[i],
+				DocumentID:        documentIDs[i],
 				Rand:              rand.Int32(),
 			},
 			DataSize: dataSizes[i],
@@ -225,6 +231,31 @@ func deduplicateRechecks(
 	documentIDs []bson.RawValue,
 	dataSizes []int,
 ) ([]string, []string, []bson.RawValue, []int) {
+
+	/*
+		for i := len(dbNames) - 1; i >= 0; i-- {
+			for j := i - 1; j >= 0; j-- {
+				if dbNames[i] != dbNames[j] {
+					continue
+				}
+
+				if collNames[i] != collNames[j] {
+					continue
+				}
+
+				if !documentIDs[i].Equal(documentIDs[j]) {
+					continue
+				}
+
+				dbNames = slices.Delete(dbNames, i, 1+i)
+				collNames = slices.Delete(collNames, i, 1+i)
+				documentIDs = slices.Delete(documentIDs, i, 1+i)
+				dataSizes = slices.Delete(dataSizes, i, 1+i)
+				break
+			}
+		}
+	*/
+
 	dedupeMap := map[string]map[string]map[string]int{}
 
 	uniqueElems := 0
diff --git a/internal/verifier/recheck_test.go b/internal/verifier/recheck_test.go
index e6b5ff81..eabc8c1d 100644
--- a/internal/verifier/recheck_test.go
+++ b/internal/verifier/recheck_test.go
@@ -253,7 +253,7 @@ func (suite *IntegrationTestSuite) TestManyManyRechecks() {
 	verifier.SetNumWorkers(10)
 	ctx := suite.Context()
 
-	docsCount := 20_000_000
+	docsCount := 12_000_000
 
 	suite.T().Logf("Inserting %d rechecks …", docsCount)