There are two websites, one live one under development. I am porting a site to Zend Framework (for maintainability/integration purposes).
The original (live) site has seamless page loads - it will load, then update the content on the screen while keeping the background image, navigation etc on the page.
The ported site (development) "flashes" completely white for a brief moment then all of the content appears simultaneously.
From what I understand, this is not a FOUC (flash of unstyled content). The content on both of the sites always appears fully styles with all CSS rules. The two sites look identical when rendered, they use the same images, css, and HTML markup. The only difference is one (development) is being served by Zend Framework and the other (live) by procedural PHP.
What are the main causes for this, and is this a known bug/configuration issue with ZF? I've had this problem before without using ZF and did not resolve it.
Thanks for your help.
Alright, I accepted an answer prematurely. What was causing this issue was in fact SWFObject!! I noticed this when developing for a new site, and it was exhibiting the same behavior. I believe this only happens in version 2+, but for anyone else that has the problem of the background flashing between page loads (as opposed to displaying all the rendered HTML at once) and happens to have swfobject being called on those pages - remove it and give it a go. It may just be your problem too.
To clarify, I had updated to a more recent version of SWFObject when porting the site over.