extremely slow performance

I’ll try to write this shortly.
Fix this piece of garbage, the program freezes for a few decades when i try zooming in when there’s a hour of audio or even worse when i listen and then zoom. It’s slow when i slide the slidebar too… I go mental when i work with this program, and by the way i can’t do anything, because this is the only program i know how to work on, and i don’t need and want to spend 100$ for other programs. So pleeeease help me fix the horrible lag. What should i do to make it at least usable…??
I have Xeon e5450 cpu and 4gb ram. What else do i need…??