diff --git a/src/enc/alpha.c b/src/enc/alpha.c
index 5ba04149..b6168cdf 100644
--- a/src/enc/alpha.c
+++ b/src/enc/alpha.c
@@ -81,8 +81,10 @@ static int EncodeLossless(const uint8_t* const data, int width, int height,
   WebPConfigInit(&config);
   config.lossless = 1;
   config.method = effort_level;  // impact is very small
-  // Set a moderate default quality setting for alpha.
-  config.quality = 10.f * effort_level;
+  // Set a low default quality for encoding alpha. Ensure that Alpha quality at
+  // lower methods (3 and below) is less than the threshold for triggering
+  // costly 'BackwardReferencesTraceBackwards'.
+  config.quality = 8.f * effort_level;
   assert(config.quality >= 0 && config.quality <= 100.f);
 
   ok = VP8LBitWriterInit(&tmp_bw, (width * height) >> 3);
diff --git a/src/enc/backward_references.c b/src/enc/backward_references.c
index db4f430d..e40182e0 100644
--- a/src/enc/backward_references.c
+++ b/src/enc/backward_references.c
@@ -780,8 +780,8 @@ int VP8LGetBackwardReferences(int width, int height,
 
   // Choose appropriate backward reference.
   if (lz77_is_useful) {
-    // TraceBackwards is costly. Don't execute it at lower quality (q <= 10).
-    const int try_lz77_trace_backwards = (quality > 10);
+    // TraceBackwards is costly. Don't execute it at lower quality.
+    const int try_lz77_trace_backwards = (quality >= 25);
     *best = refs_lz77;   // default guess: lz77 is better
     VP8LClearBackwardRefs(&refs_rle);
     if (try_lz77_trace_backwards) {