My project is currently using a svn repository which gains several hundred new revisions per day. The repository resides on a Win2k3-server and is served through Apache/mod_
Maybe you should consider improving your workflow.
I don't know if a repos will have perf issues in these conditions, but you ability to go back to a sane revision will.
In your case, you may want to include a validation process, so a team commit in a team leader repo, and each of them commit to the team manager repo who commit to the read-only clean company repos. You have make a clean selection at it stage of what commit must go to the top.
This way, anybody can go back to a clean copy, with an easy to browse history. Merge are much easier, and dev can still commit their mess as much as they want.