Big lots are unplayable

I am unable to utilise any big lots, 40x40 + as the game becomes unplayable, building anything gets buggy and I can't delete things, if it's a pre-built house, the gameplay is awful with Sims just standing around. Threw a party and all the guests just would not leave but wouldn't do anything to satisfy their needs so had to use cheats to prevent an entire family from dying.

Nothing like that happens at all on smaller lots.