Mac OS X 10.6 - Smooth scrolling - Y U NO ON 10.6.8?

While we`re all watching OSX 10.9`s development - yes, it looks pretty solid and some are saying it`s the more consistent OSX update after Snow Leopard, I`m coming here to share a point with you guys.

I`ve just finished reinstalling Mac OS 10.6, in fact I`m with the 10.6.3 version and it has a really really smooth scrolling on system navigation and web-browsing in general such as on Chrome whereas I`ve noticed that using Chrome or even Firefox (wich seemed the lighter browser on SL) on the latest Snow Leopard software update, it gets a really annoying clunky not-so-glass-smooth browsing at all. The same applies to system scrolling and navigating as well. Very light as soon as you start using Snow Leopard but starts to feel worse right after installing the latest software updates,

I`m wondering why is that. Do anyone figure that out?