Javascript related problems when using old versions of IE and a proxy server I have a site that is fairly javascript heavy.

It uses the edit module with some custom javascript overrides, some other plugins like fancy scrollbars, flexslider, image cropping, etc. as well as a bunch of custom js that does alot of ajax loading of content.

The homepage is basically a solr+facetapi search page that returns a huge grid of images, which are effectively cropped &amp; positioned with js after they load (using imagesLoaded to wait before processing).

In all modern browsers everything works fine.
In IE when not using a proxy, everything works fine.
In IE &lt;= 10 strange things happen.

Normally what happens is the page starts loading and the images start appearing individually as they have loaded.

With IE + proxy the page starts loading and then seems to stop, while all the js &amp; images are loading in the background, then after about 30 seconds (much, much longer than the page would take to fully load normally) all of the images appear at once.

Also, normally as images load in the are visibility: hidden, cropped &amp; positioned and then are visibility: visible, but in this case not all of the images end up with visibility: visible, but the images have loaded in, you can see them with developer tools tweaking of css.

Enabling or disabling of js/css aggregation doesn't make a difference, nor does cache clearing.
After a little debugging I noticed that the imagesLoaded plugin was not firing at all until the end and then was firing for all images at once, instead of normally it firing as each image loads, but there didn't seem to be any reason for this.

Setting the proxy server to "cache deny all" seemed to help the problem but it wasn't as good as it is normally in non-IE browsers (IE11 seems fine too).

Has anyone seen behaviour like this before or does anyone have any ideas of things to investigate?

TL;DR:
I have a site where everything loads normally except for users running IE &lt;= 10 and a proxy, in which case the page loads extremely slowly and javascript doesn't run as expected.

Has anyone seen anything similar or have any ideas on what it might be.
This was seemingly a server specific issue regarding a server I am not the maintainer of so I never got to the bottom of the exact cause (which is annoying because I like to know), however I eventually got around it by using the jQuery Lazy Load plugin to load the images.