Added a patch to help slow down the scroll devices that fire too fast. This new code reduces the number of 'canvas-scroll' events that fire and slows down the zoom process.

src/openseadragon.js

@@ -255,6 +255,11 @@
   * @property {Boolean} [preserveImageSizeOnResize=false]
   *     Set to true to have the image size preserved when the viewer is resized. This requires autoResize=true (default).
   *
+  * @property {Number} [minScrollDelta=3]
+  *     Number of milliseconds between canvas-scroll events. This value helps normalize the rate of canvas-scroll
+  *     events between different devices, causing the faster devices to slow down enough to make the zoom control
+  *     more manageable.
+  *
   * @property {Number} [pixelsPerWheelLine=40]
   *     For pixel-resolution scrolling devices, the number of pixels equal to one scroll line.
   *
@@ -1003,6 +1008,7 @@ if (typeof define === 'function' && define.amd) {
             pixelsPerWheelLine:     40,
             autoResize:             true,
             preserveImageSizeOnResize: false, // requires autoResize=true
+            minScrollDelta:         3,
 
             //DEFAULT CONTROL SETTINGS
             showSequenceControl:     true,  //SEQUENCE

src/viewer.js

@@ -2735,9 +2735,20 @@ function onCanvasPinch( event ) {
     return false;
 }
 
+var lastScroll = new Date().getTime();
 function onCanvasScroll( event ) {
     var gestureSettings,
-        factor;
+        factor,
+        thisScroll,
+        deltaScroll;
+
+    /* Certain scroll devices fire the scroll event way too fast so we are injecting a simple adjustment to keep things
+     * partially normalized. If we have already fired an event within the last 'minScrollDelta' milliseconds we skip
+     * this one and wait for the next event. */
+    thisScroll = new Date().getTime();
+    deltaScroll = thisScroll - lastScroll;
+    if (deltaScroll > this.minScrollDelta) {
+        lastScroll = thisScroll;
 
         if ( !event.preventDefaultAction && this.viewport ) {
             gestureSettings = this.gestureSettingsByDeviceType( event.pointerType );
@@ -2771,6 +2782,7 @@ function onCanvasScroll( event ) {
             shift: event.shift,
             originalEvent: event.originalEvent
         });
+    }
 
     if (gestureSettings && gestureSettings.scrollToZoom) {
         //cancels event