Firstly, the speed of the site is not dependent on your connectionspeed because the file really is only less than 500 kb
no more than a HTML page
The use of filters in Flash 8 however requires your processor to have quite a bit of work so maybe that is a problem if it's a slower type of processor you have!
For gingerbroke the problem is propably that you don't have Flashplayer 8 installed or miss the latest plugin in Firefox... I never encountered this problem on any PC running Flashplayer 8 even in Opera and Safari browsers it all works well... only if the correct flashplayer is installed!