My old IBM T21 suffered almost the same issues, tried to roll back the updates and even tried to install XP SP3 without any good performance change.
I had to reinstall Windows XP...

I believe it's a waste of time trying to troubleshoot performance stuff under a multipatched old install windows if you just can reinstall and get a fresh registry.

saludos.


--
"It is human nature to think wisely and act in an absurd fashion."

"Todo el desorden del mundo proviene de las profesiones mal o mediocremente servidas"