Best computer parts for simulations

I am a college freshman, and am working with a professor on some simulation work in optics. I didn't expect to be doing this until at least next year, so I only have a rather bad laptop. I am looking into building a new computer, and want to know what the most important parts for simulation work are. I am doing the simulations in Matlab right now, but that may change to python as I go on. I am just getting used to doing basic simulations now, and am already running into performance issues that slow me down considerably, including one crash due to insufficient ram.