Mercurial slow, impoosible to clone/pull/push

[junk2 at skjaerris.com]

Hi All

I have a mercurial repository, which includes 2 xml files..
Par1.xml (size approx 1.5 MB) (600 revisions)
Par2.xml (size approx 5 MB) (1200 revisions)

It has been like that for some time, but lately I am struggling by 
making clone/pull/push from the mercurial repository. When I do a clone 
it's hanging when it reaches these 2 xml files, sometimes it goes though 
after 3-5 minutes other times it fails.

Can it be true the Mercurial cant handle a 5MB file with many revisions? 
OR where should I find this problem. THe server is running windows and 
IIS, and has 16 cores and 32GB ram.

- Ulrik