IMHO it's a very good idea, unless you try mod_perl. Then you will probably say 'Ok - it runs very fast, but occupies some extra memory'. What then?
mod_perl is really great, and in some cases IT IS the best solution. If your forum is small (as you wrote), then you should consider generating static HTML files whenever something new is added to the forum...
If you run Linux you can try to accelerate your web with httpd kernel support (yes - it works only with static files, dynamic requests are still passed to apache or whatever you use)...
Of course search engines, etc. must remain dynamic, but that's another storry.

Conclusion:
You have to measure yourself which solution would be better for you. I use both of them. When there is anything that has to be generated dynamically (and i can't avoid it), i use mod_perl (mostly), but when i have to modify content once/few times a day i use generated html files ;-) That's all!

Greetz, Tom.