While testing a javascript-heavy frameset-based learning module, users complained bitterly about the white frameset background flashing at them before each page loaded, particularly in IE. A related issue was that graphics were not preloading properly in IE, so mouseovers often resulted in a white flash or a brief appearance of a "no-image" icon. Sometimes the hover image would simply never load.

Using frames is unavoidable for this module because there must be a persistent frame to store scoring and page data. So, I needed to find ways to speed up page load, and fix the flashing.

After a lot of research I found this link: Stop Image Flicker with Cache-Control Extensions.

A description of the Internet Explorer caching bug is here

I implemented the change on our IIS content server, and it worked like a charm! It makes a huge difference in both the preloading issue and the speed of page loads in general.