--- a/netwerk/protocol/http/nsHttpChannel.cpp
+++ b/netwerk/protocol/http/nsHttpChannel.cpp
@@ -2551,20 +2551,21 @@ nsHttpChannel::OpenCacheEntry(bool using
     }
     else {
         rv = cacheStorageService->DiskCacheStorage(info,
             mChooseApplicationCache || (mLoadFlags & LOAD_CHECK_OFFLINE_CACHE),
             getter_AddRefs(cacheStorage));
     }
     NS_ENSURE_SUCCESS(rv, rv);
 
-    if (mLoadAsBlocking || mLoadUnblocked ||
-        (mLoadFlags & LOAD_INITIAL_DOCUMENT_URI)) {
+    // Don't consider mLoadUnblocked here, since it's not indication of a demand
+    // to load prioritly. It's mostly used to load XHR requests, but those should
+    // not be considered as influencing the page load performance.
+    if (mLoadAsBlocking || (mLoadFlags & LOAD_INITIAL_DOCUMENT_URI))
         cacheEntryOpenFlags |= nsICacheStorage::OPEN_PRIORITY;
-    }
 
     // Only for backward compatibility with the old cache back end.
     // When removed, remove the flags and related code snippets.
     if (mLoadFlags & LOAD_BYPASS_LOCAL_CACHE_IF_BUSY)
         cacheEntryOpenFlags |= nsICacheStorage::OPEN_BYPASS_IF_BUSY;
 
     rv = cacheStorage->AsyncOpenURI(
         openURI, mPostID ? nsPrintfCString("%d", mPostID) : EmptyCString(),