--- a/toolkit/mozapps/downloads/content/downloads.js
+++ b/toolkit/mozapps/downloads/content/downloads.js
@@ -62,18 +62,18 @@ let gDownloadListener = null;
 let gDownloadsView = null;
 let gSearchBox = null;
 let gSearchTerms = "";
 let gBuilder = 0;
 
 // Control the performance of the incremental list building by setting how many
 // milliseconds to wait before building more of the list and how many items to
 // add between each delay.
-const gListBuildDelay = 100;
-const gListBuildChunk = 10;
+const gListBuildDelay = 300;
+const gListBuildChunk = 3;
 
 // If the user has interacted with the window in a significant way, we should
 // not auto-close the window. Tough UI decisions about what is "significant."
 var gUserInteracted = false;
 
 // These strings will be converted to the corresponding ones from the string
 // bundle on startup.
 let gStr = {
@@ -1183,17 +1183,17 @@ function stepListBuilder(aNumItems) {
   }
 
   // Add another item to the list if we should; otherwise, let the UI update
   // and continue later
   if (aNumItems > 1) {
     stepListBuilder(aNumItems - 1);
   } else {
     // Use a shorter delay for earlier downloads to display them faster
-    let delay = Math.min(gDownloadsView.itemCount, gListBuildDelay);
+    let delay = Math.min(gDownloadsView.itemCount * 10, gListBuildDelay);
     gBuilder = setTimeout(stepListBuilder, delay, gListBuildChunk);
   }
 }
 
 /**
  * Add a download to the front of the download list
  *
  * @param aDownload