I decided that for now, rather than rewriting the posting/reading routines from scratch to be as efficient as possible, I'm going with the more expedient route of modifying existing routines to extract more efficiency out of them and saving the rewrites for when the status quo is finally acceptable.
That means I'm going to be implementing new versions of each minor change throughout the day. Please let me know if you see any problems. I'm currently working on read_msg and have implemented some fairly small changes.
I'll at least test the Premium user scenario before implementing. If you and Matt are available to test the free and non-logged in scenarios, that'd be beautiful.