I have these tests to check start render time using Sao Paulo/Brasil locate:
Firefox - 5.173s - http://www.webpagetest.org/result/130815_CQ_45R/
IE 9 - 1.649s - http://www.webpagetest.org/result/130815_48_45V/
Always start render time on Firefox is higher.
I was trying to understand why. I changed the location to Dulles:
Firefox - 2.482s - http://www.webpagetest.org/result/130815_9S_49H/
IE 9 - 1.359s - http://www.webpagetest.org/result/130815_JN_4EC/
Why test for Firefox decreased so much? Anyone have any idea how to decrease start render on Firefox, please?
It looks like you are doing something REALLY expensive in your site js. The Sao Paulo location has a somewhat slower CPU which probably accounts for the difference and the fact that it’s a gap in processing and the CPU utilization is at 100% pretty much guarantees that it’s the js code.
You can try loading the code up in Chrome’s dev tools and look at the timeline or profiler to see what it is doing that is expensive or disabling parts of it until you find the piece that is causing the issue.
It looks somewhat better with the external js blocked: http://www.webpagetest.org/result/130815_CN_a8e2404f22aef2182242e6b9cff707b3/ but there’s still quite a gap in there. Running with js completely disabled is also still looking pretty painful: http://www.webpagetest.org/result/130815_3W_f7f355731e037e79b6ee99395e2c6a47/ so it might be some painful css layout.
It’s a lot better with the css blocked and js disabled but that’s not really the same site anymore: http://www.webpagetest.org/result/130815_6M_0db5a4d358266b472e7e0f7361a77025/