Random sims coming into apartment

My sims live in a For Rent apartment and random sims just keep walking in without being invited. I have to lock the fromt door to prevent this but then when I have guests over, I unlock it and sims continue to enter my apartment. It’s not listed as a shared space or anything. 

Additionally, while playing in this apartment it’s very laggy and just crashed the game. Please fix the For Rent apartments.