I'm seeing the same problems -- Wikipedia is locked up most of the time, only responding occasionally at random, making it effectively unusable.
Netcraft reports that is is running Apache/1.3.23 (Unix) PHP/4.0.6 mod_fastcgi/2.2.12 on Linux.
There is now a severe Apache security vulnerability that affects
Apache 1.3 all versions including 1.3.24; Apache 2.0 all versions up to 2.0.36; Apache 1.2 all versions.
This looks like something that should be fixed ASAP. And it just might explain some of the problems seen.
-- Neil