May 2021
@kwohld The value you've listed isn't RAM use, it's the upper limit for the game's script heap, and it's set by default to 20 GB, not 2. (Count the zeroes again.) Changing this value is neutral at best and may be harmful, so please undo the change. Sims 3 can use ~3.7 GB RAM on its own (4 GB minus some overhead), and there's no way to increase the amount of memory available to it. That's just the nature of 32-bit apps.
I take it you're using MasterController to reset the lot? If that doesn't help, try flushing the garden items instead. Click on the ground of the lot, select MC > Object Stats > Not Inventory, select the items you want gone, and let MC delete them. This is cleaner than simply deleting them in Build or Buy mode.
May 2021
I took out some Mods that I installed about a week ago and now my game is working perfectly!