i use a p4 machine, with horrors of horrors, mint linux, which must be slowest and crashiest os ever... and pdf is quite slow on my machine... many times i have to restart the machine... and compulsorily, if a page has more than two embedded video frames ( youtube, fakebook ).
i think pdf should look to having one site theme which should work fast on the slowest available machine.
so despite me not being that familiar with current website design, i would still say the forum should replace javascript with flash completely... flash has its scripting ( actionscript ), and flash visuals are faster than anything involving js... there are flash video websites which work when js is disabled.
choose "default style"... it works for me.