I'd hate having to do that manually by loading up a script, and I don't have access to the crontab task scheduler, so I prefer doing it dynamically.
Yep, my profile pages load quite slow, mostly because this is just a small part of a shared server and really underpowered. The letter statistics do not account for a major part of the generation time, though. Granted, that's because there are some other modifications in there.
Overall, I think it's the best way to do it in a case similar to mine.