I've tested Ubuntu 11.04 clean installs in two computers, an eeepc netbook and a hp pavilion t3010.es, which is an old desktop computer (6 or 7 years) with the specs of a netbook approximately. The issue is that 11.04 runs on these two much slower than 10.10 did, almost as Windows 7 in the desktop pc. By slower I consider a general decrease on the overall performance: longer boot time, longer log in, longer startup time on almost every application I use (chromium, nautilus, banshee,... common use ones), much longer update time... I tried both unity and classic desktop modes, with barely no difference in performance on both. Is this normal? Thanks!
11.04 for me is a bit slower than 10.10 but 11.04 does lean on a lot of graphical stuff with Unity (not so much with classic though so I find it odd both seem slower).
You did not specify where you consider 11.04 to be slower than 10.10
So in short my answer would be: yes, it is slower but not by alot.
A few pointers:
I hope you can figure out if something is wrong with your install!
Desktop compositing is enabled by default. If it's doing a lot of compositing work in software, that could be one very probable reason(imo).