On my hosting environment I run a nop 4.3 with OutOfProcess hosting model.
I asked for InProcess and they had to switch the app pool from 32 bit to 64 otherwise it wouldn't run at all.
After the switch from 32 to 64 and from OutOfProcess to InProcess the site would load really slowly. So we switched back to 32 and OutOfProcess.
Don't know if that helps.