Im creating an iOS game and I thought I was done until I test ran it on the iPad Retina simulator, and its extremely laggy. Is that a simulator glitch, or will it actually not work on the Retina iPad? I tried looking up if it was necessary and couldn't find an exact answer.
You shouldn't be using the simulator for making any kind of judgment around performance. It's a simulator, not an actual device. It doesn't represent the actual conditions you'll be experiencing in hardware, and there are vast differences in terms of graphics and the rendering pipeline. If you're not testing your app on a hardware device you're doing a disservice to your potential users.
Do bear in mind the vast majority of devices being sold right now are retina. Many graphically rich games are able to support the hardware, so I suspect what you're seeing is either a) due to the simulator, or b) can be fixed with some optimisation.