diff --git a/storage/cache/log_tile.go b/storage/cache/log_tile.go
index 356b7f9991..2def12312e 100644
--- a/storage/cache/log_tile.go
+++ b/storage/cache/log_tile.go
@@ -15,6 +15,7 @@
 package cache
 
 import (
+	"encoding/binary"
 	"fmt"
 
 	"github.com/google/trillian/merkle/compact"
@@ -61,12 +62,7 @@ func PopulateLogTile(st *storagepb.SubtreeProto, hasher hashers.LogHasher) error
 		// Don't put leaves into the internal map and only update if we're rebuilding internal
 		// nodes. If the subtree was saved with internal nodes then we don't touch the map.
 		if id.Level > 0 && len(st.Leaves) == maxLeaves {
-			subDepth := logStrataDepth - int(id.Level)
-			// TODO(Martin2112): See if we can possibly avoid the expense hiding inside NewNodeIDFromPrefix.
-			nodeID := tree.NewNodeIDFromPrefix(st.Prefix, subDepth, int64(id.Index), logStrataDepth, maxLogDepth)
-			sfx := nodeID.Suffix(len(st.Prefix), int(st.Depth))
-			sfxKey := sfx.String()
-			st.InternalNodes[sfxKey] = hash
+			st.InternalNodes[toSuffix(id)] = hash
 		}
 	}
 
@@ -74,15 +70,13 @@ func PopulateLogTile(st *storagepb.SubtreeProto, hasher hashers.LogHasher) error
 	cr := fact.NewEmptyRange(0)
 
 	// We need to update the subtree root hash regardless of whether it's fully populated
-	for leafIndex := int64(0); leafIndex < int64(len(st.Leaves)); leafIndex++ {
-		nodeID := tree.NewNodeIDFromPrefix(st.Prefix, logStrataDepth, leafIndex, logStrataDepth, maxLogDepth)
-		sfx := nodeID.Suffix(len(st.Prefix), int(st.Depth))
-		sfxKey := sfx.String()
+	for leafIndex := uint64(0); leafIndex < uint64(len(st.Leaves)); leafIndex++ {
+		sfxKey := toSuffix(compact.NewNodeID(0, leafIndex))
 		h := st.Leaves[sfxKey]
 		if h == nil {
-			return fmt.Errorf("unexpectedly got nil for subtree leaf suffix %s", sfx)
+			return fmt.Errorf("unexpectedly got nil for subtree leaf suffix %s", sfxKey)
 		}
-		if size, expected := int64(cr.End()), leafIndex; size != expected {
+		if size, expected := cr.End(), leafIndex; size != expected {
 			return fmt.Errorf("got size of %d, but expected %d", size, expected)
 		}
 		if err := cr.Append(h, store); err != nil {
@@ -135,3 +129,10 @@ func prepareLogTile(st *storagepb.SubtreeProto) error {
 	}
 	return nil
 }
+
+func toSuffix(id compact.NodeID) string {
+	depth := logStrataDepth - int(id.Level)
+	var index [8]byte
+	binary.BigEndian.PutUint64(index[:], id.Index<<(maxLogDepth-depth))
+	return tree.NewSuffix(uint8(depth), index[:]).String()
+}
diff --git a/storage/cache/subtree_cache_test.go b/storage/cache/subtree_cache_test.go
index a70e5b6752..2b6a764660 100644
--- a/storage/cache/subtree_cache_test.go
+++ b/storage/cache/subtree_cache_test.go
@@ -241,9 +241,7 @@ func TestRepopulateLogSubtree(t *testing.T) {
 			t.Fatalf("merkle tree update failed: %v", err)
 		}
 
-		nodeID := tree.NewNodeIDFromPrefix(s.Prefix, logStrataDepth, numLeaves-1, logStrataDepth, maxLogDepth)
-		_, sfx := nodeID.Split(len(s.Prefix), int(s.Depth))
-		sfxKey := sfx.String()
+		sfxKey := toSuffix(compact.NewNodeID(0, uint64(numLeaves)-1))
 		s.Leaves[sfxKey] = leafHash
 		if numLeaves == 1<<uint(defaultLogStrata[0]) {
 			s.InternalNodeCount = uint32(len(cmtStorage.InternalNodes))
@@ -285,9 +283,7 @@ func BenchmarkRepopulateLogSubtree(b *testing.B) {
 	for i := 0; i < 256; i++ {
 		leaf := []byte(fmt.Sprintf("leaf %d", i))
 		hash := hasher.HashLeaf(leaf)
-		nodeID := tree.NewNodeIDFromPrefix(s.Prefix, logStrataDepth, int64(i), logStrataDepth, maxLogDepth)
-		_, sfx := nodeID.Split(len(s.Prefix), int(s.Depth))
-		s.Leaves[sfx.String()] = hash
+		s.Leaves[toSuffix(compact.NewNodeID(0, uint64(i)))] = hash
 	}
 
 	for n := 0; n < b.N; n++ {