There can be two different causes. One is the teleport 'memory' we use to go back to the right place when exiting. I will make a small change there that could solve it. If it does not work, then the cause is memory handling of SA:MP, which might not be designed for the number of houses and interiors we use. In that case we will have to hope SA:MP improves the handling so it will work better in 0.2.