diff --git a/lib/storage/part_search.go b/lib/storage/part_search.go
index 88e92c501b..572b45553b 100644
--- a/lib/storage/part_search.go
+++ b/lib/storage/part_search.go
@@ -69,7 +69,7 @@ func (ps *partSearch) Init(p *part, tsids []TSID, tr TimeRange) {
 		if isInTest && !sort.SliceIsSorted(tsids, func(i, j int) bool { return tsids[i].Less(&tsids[j]) }) {
 			logger.Panicf("BUG: tsids must be sorted; got %+v", tsids)
 		}
-		// take ownership of of tsids.
+		// take ownership of tsids.
 		ps.tsids = tsids
 	}
 	ps.tr = tr
@@ -120,14 +120,38 @@ func (ps *partSearch) nextTSID() bool {
 	return true
 }
 
+func (ps *partSearch) skipTSIDsSmallerThan(tsid *TSID) bool {
+	if !ps.BlockRef.bh.TSID.Less(tsid) {
+		return true
+	}
+	if !ps.nextTSID() {
+		return false
+	}
+	if !ps.BlockRef.bh.TSID.Less(tsid) {
+		// Fast path: the next TSID isn't smaller than the tsid.
+		return true
+	}
+
+	// Slower path - binary search for the next TSID, which isn't smaller than the tsid.
+	tsids := ps.tsids[ps.tsidIdx:]
+	ps.tsidIdx += sort.Search(len(tsids), func(i int) bool {
+		return !tsids[i].Less(tsid)
+	})
+	if ps.tsidIdx >= len(ps.tsids) {
+		ps.tsidIdx = len(ps.tsids)
+		ps.err = io.EOF
+		return false
+	}
+	ps.BlockRef.bh.TSID = ps.tsids[ps.tsidIdx]
+	ps.tsidIdx++
+	return true
+}
+
 func (ps *partSearch) nextBHS() bool {
 	for len(ps.metaindex) > 0 {
-		// Optimization: skip tsid values smaller than the minimum value
-		// from ps.metaindex.
-		for ps.BlockRef.bh.TSID.Less(&ps.metaindex[0].TSID) {
-			if !ps.nextTSID() {
-				return false
-			}
+		// Optimization: skip tsid values smaller than the minimum value from ps.metaindex.
+		if !ps.skipTSIDsSmallerThan(&ps.metaindex[0].TSID) {
+			return false
 		}
 		// Invariant: ps.BlockRef.bh.TSID >= ps.metaindex[0].TSID
 
@@ -247,7 +271,7 @@ func (ps *partSearch) searchBHS() bool {
 		if bh.TSID.MetricID != tsid.MetricID {
 			// tsid < bh.TSID: no more blocks with the given tsid.
 			// Proceed to the next (bigger) tsid.
-			if !ps.nextTSID() {
+			if !ps.skipTSIDsSmallerThan(&bh.TSID) {
 				return false
 			}
 			continue
diff --git a/lib/storage/part_search_timing_test.go b/lib/storage/part_search_timing_test.go
new file mode 100644
index 0000000000..cacd73bd70
--- /dev/null
+++ b/lib/storage/part_search_timing_test.go
@@ -0,0 +1,61 @@
+package storage
+
+import (
+	"fmt"
+	"testing"
+)
+
+func BenchmarkPartSearch(b *testing.B) {
+	for _, sparseness := range []int{1, 2, 10, 100} {
+		b.Run(fmt.Sprintf("sparseness-%d", sparseness), func(b *testing.B) {
+			benchmarkPartSearchWithSparseness(b, sparseness)
+		})
+	}
+}
+
+func benchmarkPartSearchWithSparseness(b *testing.B, sparseness int) {
+	blocksCount := 100000
+	rows := make([]rawRow, blocksCount)
+	for i := 0; i < blocksCount; i++ {
+		r := &rows[i]
+		r.PrecisionBits = defaultPrecisionBits
+		r.TSID.MetricID = uint64(i * sparseness)
+		r.Timestamp = int64(i) * 1000
+		r.Value = float64(i)
+	}
+	tr := TimeRange{
+		MinTimestamp: rows[0].Timestamp,
+		MaxTimestamp: rows[len(rows)-1].Timestamp,
+	}
+	p := newTestPart(rows)
+	for _, tsidsCount := range []int{100, 1000, 10000, 100000} {
+		b.Run(fmt.Sprintf("tsids-%d", tsidsCount), func(b *testing.B) {
+			tsids := make([]TSID, tsidsCount)
+			for i := 0; i < tsidsCount; i++ {
+				tsids[i].MetricID = uint64(i)
+			}
+			benchmarkPartSearch(b, p, tsids, tr, sparseness)
+		})
+	}
+}
+
+func benchmarkPartSearch(b *testing.B, p *part, tsids []TSID, tr TimeRange, sparseness int) {
+	b.ReportAllocs()
+	b.RunParallel(func(pb *testing.PB) {
+		var ps partSearch
+		for pb.Next() {
+			blocksRead := 0
+			ps.Init(p, tsids, tr)
+			for ps.NextBlock() {
+				blocksRead++
+			}
+			if err := ps.Error(); err != nil {
+				panic(fmt.Errorf("BUG: unexpected error: %s", err))
+			}
+			blocksWant := len(tsids) / sparseness
+			if blocksRead != blocksWant {
+				panic(fmt.Errorf("BUG: unexpected blocks read; got %d; want %d", blocksRead, blocksWant))
+			}
+		}
+	})
+}