why does my 2.5 LAG?

[imaginethis1]

i have installed numerous manila 2.5 roms, and after people are telling me it runs as smoothly as 2.1, i still don't believe it. most of the time my lag comes when navigating through the tabs...especially from the Home screen.

i might be doing something wrong, but i really dunno what it could be. is anyone else experiencing this lag coming out of home screen? and if so, why continue to build 2.5 roms??