openlayers/openlayers — pull request #1327 by matthewma (2014-05-13 19:46:03+00:00)
Title: Update featureclick.js

events/featureclick.js uses technique layer.div.style.display = "none" and layer.div.style.display = "block" to loop through layers to find all features that exists on certain screen x,y point;

However, currently, on Chrome 34.0.1847.131m and 35.0.1916.99 beta-m;
The hide and show technique triggers mousemove event, which causes the onMousemove method get called constantly, resulting a big performance impact. This won't happen on Internet Explorer and Firefox.
An test can be found http://jsfiddle.net/er7hm/2/;

The code below prevents onMousemove got called constantly by checking if the cursor actually moved.
It solves the problem. However, i don't know if the issue will be fixed by Chrome or if I have a valid fix.