This test result shows that 32 bit Ubuntu is better for static web page serving through Apache:
http://www.phoronix.com/scan.php?pag...x86_1304&num=4

(Look at bottom of the pages)

But this one shows 64 bit is better:
http://www.phoronix.com/scan.php?pag...u_32_pae&num=1

What's the cause of different results? Is it 1GB and 4GB RAMs?

Also, won't 64 bit take more space in CPU's cache and thus decrease the web-page serving performance?