diff --git a/content/completion.js b/content/completion.js
index d62e1321..68cca9dd 100644
--- a/content/completion.js
+++ b/content/completion.js
@@ -27,6 +27,7 @@ the terms of any one of the MPL, the GPL or the LGPL.
 }}} ***** END LICENSE BLOCK *****/
 
 // An eval with a cleaner lexical scope.
+// TODO: that shows up in ":echo modules", can we move it "inside" the Completion class? --mst
 const EVAL_TMP = "__liberator_eval_tmp";
 function __eval(__liberator_eval_arg, __liberator_eval_tmp)
 {
@@ -201,6 +202,7 @@ function Completion() //{{{
 
             if (key in cache)
                 return cache[key];
+
             try
             {
                 return cache[key] = __eval(arg, tmp);
@@ -675,6 +677,13 @@ function Completion() //{{{
              return [];
         },
 
+        // cancel any ongoing search
+        cancel: function()
+        {
+            if (completionService)
+                completionService.stopSearch();
+        },
+
         // discard all entries in the 'urls' array, which don't match 'filter
         // urls must be of type [["url", "title"], [...]] or optionally
         //                      [["url", "title", keyword, [tags]], [...]]
@@ -1187,6 +1196,7 @@ function Completion() //{{{
                 else if (c == "l" && completionService) // add completions like Firefox's smart location bar
                 {
                     completionService.stopSearch();
+                    //dump("searching for " + filter + "\n");
                     completionService.startSearch(filter, "", historyResult, {
                         onSearchResult: function onSearchResult(search, result) {
                             historyResult = result;
diff --git a/content/ui.js b/content/ui.js
index 8e32b27b..07907bd9 100644
--- a/content/ui.js
+++ b/content/ui.js
@@ -153,6 +153,7 @@ function CommandLine() //{{{
     var promptCompleter = null;
 
     liberator.registerCallback("change", modes.EX, function (command) {
+        completion.cancel(); // cancel any previous completion function
         if (options.get("wildoptions").has("auto"))
             autocompleteTimer.tell(command);
         else
diff --git a/content/util.js b/content/util.js
index da580861..f4770baa 100644
--- a/content/util.js
+++ b/content/util.js
@@ -76,6 +76,7 @@ const util = { //{{{
         }
     },
 
+    // TODO: class could have better variable names/documentation
     Timer: function Timer(minInterval, maxInterval, callback)
     {
         let timer = Components.classes["@mozilla.org/timer;1"]
@@ -88,6 +89,7 @@ const util = { //{{{
             this.latest = 0;
             /* minInterval is the time between the completion of the command and the next firing. */
             this.doneAt = Date.now() + minInterval;
+
             try
             {
                 callback(this.arg);
@@ -110,9 +112,10 @@ const util = { //{{{
             if (now > this.doneAt && this.doneAt > -1)
                 timeout = 0;
             else if (this.latest)
-                timeout = Math.min(minInterval, this.latest - now);
+                timeout = minInterval;
             else
                 this.latest = now + maxInterval;
+
             timer.initWithCallback(this, Math.max(timeout, 0), timer.TYPE_ONE_SHOT);
             this.doneAt = -1;
         };