Click blocking software

Hey everyone, What's the best click blocking software in terms of performance, both at the server end, and client end? I'm a bit nervous about implementing something like this because in the past I have, and it slowed my VPS, and other hosting systems to a crawl. Not cool.

-S

Click blocking? Is this a software which prevents some one from click bombing your site?
If so, it could be waay useful, yea
Maybe you could just hire a freelancer to code a script for you to do the job.

Anyone?