It would be really helpful if you provided more information about your computer specs for us to know if it’s a hardware issue or not. Things like your processor speed, graphics card, and available RAM make a big difference in performance.
You say that you are fairly new to editing so my first instinct is that you are probably not using a fast external drive as your media drive. If that’s the case, I suggest you buy (or borrow) a dedicated drive for this purpose. If you are using an external drive, what speed is it (it should be at least 7200 RPM) and how is it connected to your system?
HTH
Gary