[Ubuntu-BD] a question about ubuntu 9.04

[~Split_Fire~]

Hi,

I 've another question, I 've core duo 1.83 GHz machine with 512 RAM. I used
ubuntu 7.10 and 8.04 which were running smoothely. But after installing 9.04
it doesn't seem to be faster as before as I click on any minimized window or
browser, it doesn't maximized smoothely. In system monitor, it shows almost
39% memory have been occupied without running any application. Can I make it
faster?

Thanks again.