Potential fix to slowness in IE7 / Vista?

Question

Hello.
Someone brought this to my attention. A page created with iWeb (not sure of version) was taking forever to load in IE7 on Vista. The server seemed to come back, but an excessive amount of javascript running onLoad was causing IE to hang.
I noticed a topic posted here: http://discussions.apple.com/thread.jspa?threadID=1084667 ... and I was going to post my findings there, but for some reason, the topic is both unanswered and archived... seemingly still valid, 3 years later.
Anyway, at around line 332-343 of iWebSite.js (again, not sure of the version it was created with -- the line numbers might vary for different versions?) a function, fixAllIEPNGs, exists that takes each image with a PNG extension and applies the AlphaImageLoader css filter to get transparency working.
AlphaImageLoader is only required for earlier versions of IE (between 5.5 - 6.0 if I recall correctly) and is PAINFULLY slow... Normally it takes a couple thousand GIF/JPG on a page before you notice any lag, but with the alpha image loader, it takes only a half dozen or so before things slow to a crawl.
Thing is, the function runs for all versions of IE, where it really only needs to be applied to versions < 7. So... the suggested, completely untested, fix I provided to my friend (I should have prefaced saying I don't actually own a Mac, nor have I ever used iWeb) was to make a revisions to iWebSite.js, line 333:
replace: {detectBrowser();if(windowsInternetExplorer)
with : {if( shouldApplyCSSBackgroundPNGFix() )
That function is used in a different section and checks for IE<7. Applying this fix should speed things up in newer versions of IE and for those fools still using archaic versions of IE, they'll still get transparency on the PNG files.
Um... enjoy!

Answer 1

Nice post, thanks!