I'm hosting around 30 DNN instances on my server. Most of them consume 150-200MB of RAM and perform great. But one of them, that gets very little traffic and has no different modules than any other instance, is consuming between 500-1400MB and can sometime take several minutes and multiple tries to load, and throws Request Timed Out errors when it doesn't load. Once up and running, the site runs fine. But if I kill it's process, recycle the app pool, or restart the site, it takes a long time to load again and quickly climbs to using lots of RAM. 

This same instance was having issues on shared hosting at NewTek before I brought it over to my server. I figured it was something with their hosting but apparently not.

So now I've spent several hours trying to figure out what is different between this instance and other instances. And can't find anything obvious.
I've reapplied the 7.3.4 upgrade. I've done binary comparisons of all files. I've removed unused modules. I've compared the web.config line by line. I've checked the schedule to make sure no processes were taking extra time. I've cleared the client Dependency files and Search Files and made sure they regenerated properly. I've turned off Search indexing since it wasn't being used.I've checked it an SQL indexes are missing. 

Nothing has made any significant difference.

Any thoughts on the cause or other things I can try?