diff --git a/clang-tools-extra/clangd/index/dex/Iterator.cpp b/clang-tools-extra/clangd/index/dex/Iterator.cpp
--- a/clang-tools-extra/clangd/index/dex/Iterator.cpp
+++ b/clang-tools-extra/clangd/index/dex/Iterator.cpp
@@ -109,6 +109,9 @@
         if (Child->peek() > SyncID) {
           SyncID = Child->peek();
           NeedsAdvance = true;
+          // Reset and make sure advanceTo happens much less frequently on
+          // large posting lists. This accounts for 45-60% performance boost.
+          break;
         }
       }
     } while (NeedsAdvance);