memory leak? shows up in mongrel, not webrick

I've got an app that iterates through an array of 1000+ ActiveRecords in order to support quick AJAX filtering. When the app is running on mongrel(s), this process makes the RAM usage go through the roof (i.e., adding 50MB per iteration) and the usage never goes back down. Running on webrick, the app stabilizes at around 70MB and never goes higher no matter how many times I iterate through that array.

I've been unable to install the bleak_house gem on my dev machine (running OS X Leopard). My other attempts to profile the RAM have been fruitless so far. Any ideas? Perhaps I'm not releasing the AR objects correctly? I am a Ruby/Rails newbie.

Thanks,

DGB