It's not so much hosting (well, it is), as it is the mongo database I'm hosting. I started using mongo because, well, it's the "new hotness", and I started this project to play with new technologies. The problem is, I didn't realize at the time that 1) This would get so popular, and 2) Mongo needs to have all data in memory for it to be at all efficient.

The database is now hosting ~8gb of data and ~4gb of indexes. I'm sure I could make that more efficient, but, well, at this point it'd be a lot more work than I think it's worth. Because of that amount of data, I need to run it on an AWS server with a LOT of ram, and those are a fair bit more expensive than the other servers I'm running. Every time I've had an issue with the site being slow, it's been because of mongo running out of ram to use.

MongoDB... only once. :-P