I've built quite a large apartment lot (5x3) and the gameplay gets bumpy when all the other tennants are outside (2.4 GHz, 4GB: core 100%, RAM not full). Building it I used "SetHighestAllowedLevel 8", but when I finished, I only needed 4 levels and the roof. Is there a way of decreasing the number of levels back to 4 or 5? Of course I tried it using the cheat, but playing the lot I can still page up 3 levels above the roof. And are these excess levels cause of the bumpy gameplay?

All that cheat does is change the number of levels you're allowed. A more built-up lot will cause the game to lag more than a lot that's basically empty, but if you haven't built on the levels you enabled with the cheat, they aren't doing anything. Apartment Life just tends to be laggy for many users - myself included.

Okay, thanks, that saves me a lot of time rebuilding on a restricted lot and finding it out for myself. I'm now redesigning it on a 3x3 lot for those of us who don't have 5 GHz cpu's.

presently, I've not read or figured how to decrease the lot level safely. let's see if someone knows about it.

may avoid to preset the SetHighestAllowedLevel with a high number.
instead, may just alias it into a shorthand for convenience in the startup.cheat.

if the lot is not saved yet when the extra levels are enabled, may exit without a save and re-enter the lot if appropriate.