I play in windowed mode but not because of lag. I play that way because I can't seem to just play the sims, I also seem to feel the need to watch videos, cc shop, read the forums, etc...while I play so windowed works best for me. I have a very large screen so it works out ok. My window for the sims is larger than an average sized pc monitor screen anyway. I do a lot of graphic arts work on my pc so my hubby bought me a huge screen for multitasking. Its handy.