You can see this behavior by running the website in folder
CssBlocksRendering in the downloaded code bundle. This test has a single page that loads a single CSS file. Generation of the CSS file on the server is delayed by five seconds, using the HTTP Module
DelayModule in its
App_Code folder. When you open the page, you'll find that the window stays blank for five seconds.
One way to reduce this issue is to load your CSS files as quickly as possible. You can ...