diff --git a/js/conf/ExtensionConf.js b/js/conf/ExtensionConf.js
index a59e878..4b67f3a 100644
--- a/js/conf/ExtensionConf.js
+++ b/js/conf/ExtensionConf.js
@@ -11,6 +11,7 @@ var ExtensionConf = {
                               //       'blacklist' - work by default, problem sites need to be blocked
                               //       'whitelist' - only work if site has been specifically approved
                               //       'disabled'  - don't work at all 
+    disabledReason: "",       // if automatic aspect ratio has been disabled, show reason
     allowedMisaligned: 0.05,  // top and bottom letterbox thickness can differ by this much. 
                               // Any more and we don't adjust ar.
     allowedArVariance: 0.075, // amount by which old ar can differ from the new (1 = 100%)
@@ -18,6 +19,11 @@ var ExtensionConf = {
     timer_paused: 3000,
     timer_error: 3000,
     timer_minimumTimeout: 5,  // but regardless of above, we wait this many msec before retriggering
+    autoDisable: {            // settings for automatically disabling the extension
+      maxExecutionTime: 15,   // if execution time of main autodetect loop exceeds this many milliseconds,
+                              // we disable it.
+      consecutiveTimeoutCount: 5  // we only do it if it happens this many consecutive times
+    },
     hSamples: 640,
     vSamples: 360,
     samplingInterval: 10,     // we sample at columns at (width/this) * [ 1 .. this - 1] 
diff --git a/js/modules/ArDetect.js b/js/modules/ArDetect.js
index 2e14aa2..16f4d37 100644
--- a/js/modules/ArDetect.js
+++ b/js/modules/ArDetect.js
@@ -1381,8 +1381,20 @@ var _ard_isRunning = function(){
 }
 
 function _ard_getTimeout(baseTimeout, startTime){
-//   baseTimeout -= (performance.now() - startTime);
+  var execTime = (performance.now() - startTime);
+  
+  if( execTime > ExtensionConf.arDetect.autoDisable.maxExecutionTime ){
+    GlobalVars.arDetect.autoDisable.eventCount++;
 
+    if(GlobalVars.arDetect.autoDisable.eventCount >= ExtensionConf.arDetect.autoDisable.consecutiveTimeoutCount ){
+      Comms.sendToBackgroundScript({cmd: 'disable-autoar', reason: 'Automatic aspect ratio detection was taking too much time and has been automatically disabled in order to avoid lag.'});
+      _ard_stop();
+      return 999999;
+    }
+    
+  } else {
+    GlobalVars.arDetect.autoDisable.eventCount = 0;
+  } 
 //   return baseTimeout > ExtensionConf.arDetect.minimumTimeout ? baseTimeout : ExtensionConf.arDetect.minimumTimeout;
   
   return baseTimeout;
diff --git a/js/run/GlobalVars.js b/js/run/GlobalVars.js
index 432f5e3..5db8e17 100644
--- a/js/run/GlobalVars.js
+++ b/js/run/GlobalVars.js
@@ -22,6 +22,9 @@ var GlobalVars = {
     left: null
   },
   arDetect: {
+    autoDisable: {
+      eventCount: 0
+    },
     canvas: null,
     blackLevel: 10,
     sampleCols_current: 0,
diff --git a/js/uw-bg.js b/js/uw-bg.js
index afad743..5c71d60 100644
--- a/js/uw-bg.js
+++ b/js/uw-bg.js
@@ -212,6 +212,11 @@ function _uwbg_rcvmsg(message, sender, sendResponse){
   }
   else if(message.cmd == "disable-autoar"){
     ExtensionConf.arDetect.mode = "disabled";
+    if(message.reason){
+      ExtensionConf.arDetect.disabledReason = message.reason;
+    } else {
+      ExtensionConf.arDetect.disabledReason = '';
+    }
     Settings.save(ExtensionConf);
 //     Comms.sendToAll({cmd: "reload-settings", sender: "uwbg"});
     if(Debug.debug){
diff --git a/manifest.json b/manifest.json
index df18bd4..7981a7d 100644
--- a/manifest.json
+++ b/manifest.json
@@ -1,7 +1,7 @@
 {
   "manifest_version": 2,
   "name": "Ultrawidify",
-  "version": "2.2.4",
+  "version": "2.2.5",
   
   "icons": {
     "32":"res/icons/uw-32.png",