[CentOS] Yum uses too much resources

Hi all,

When I do a simple string search with Yum (ex. yum search *hwinfo*) my 
laptop suffers high slowness. If I open another shell-tab and execute 
top command, it shows me an extensive use of hardware resources from Yum 
(20-25% RAM and 70-85% CPU). If in the same time I'm using Firefox 
browser the performance goes down too much and even it seems the box 
it's freezed. The box become totally useless during few minutes (until 
yum command has finished or I've killed it)

More info about my old and loved laptop:

* Hardware*
Acer TravelMate 240
256RAM
Celeron 2,5 Ghz

*Software*
CentOS 4.4 Final (totally updated at current day)
Desktop default instalation (which means GNOME environment)


¿Is this behaviour "normal"? ¿What about this extensive hardware use 
from Yum?

I supose my laptop is an old-fashioned hardware but this behaviour did 
not happen when I installed Ubuntu (and I did use apt to manage sofware) 
in same machine in recent past.