Can you tell us how much RAM (Memory) you have? It's listed by clicking on the in your title bar....go to About This Mac and it's in the 1st window.
We would also like to know what size hard drive you have and how much free space is on it.
If you click on your Hard drive icon (should be upper right hand corner of your screen), or the Finder in your Dock...when the window opens it says at the bottom how much Free Space you have on your drive.
If you go to the , click on About This Mac, click on More Info... in that window. The next window says how big your hard drive is under Hardware....click on Serial-ATA.....look under Capacity:
We need to know this cause if a hard drive is too full it slows things down and creates operational difficulties.