There is clearly some difference in the behaviour which causes this apparent difference in speed. PHP however, it pretty much guaranteed to be the same speed regardless of web browser (unless you put some code in specially).
- Does this happen on your dev box? If not, you're pretty much stuffed.
- Does this happen with Javascript disabled (in both browsers)? If not, it's a client-side issue - check your JS.
- Enable logging in Apache of the request times (see docs for how to do this) (Again, on your dev box). Does MSIE make more requests than FF (for example, because it's caching less?). Do the MSIE requests take longer to process?
- Look at the traffic in a network analyser. Is there anything suspicious? There may be a TCP-level issue, or a HTTP-level problem.
These are some suggestions, but it's really quite a difficult thing.
Javascript has different performance characteristics in different browsers. Some things are faster in MSIE, some things faster in Mozilla. Disable Javascript to validate this hypothesis.
I assume you have no third party scripts or ads on your page - if you do, disable them all first- these could be doing ANYTHING including browser-sniffing etc, which is not helpful.
If you have any images, frames, scripts etc, loading from an external server, disable all of those and try again.
Anything loading from anywhere other than your box could cause anything to happen.
Mark
