macbooks been running really slow lately

New to this forum, hopefully you guys can help me out. My macbook has been running slowly recently. Programs take a while to start running, sometimes they slow down after they've been running for awhile. Deleted a bunch of stuff I had on my hard drive but that didn't do much. Though about doing a scan for spyware and whatnot but I looked into it a little bit and it seems like that shouldn't be a problem either but I don't know. Any ideas? Thanks!

Whats the spec fo the Macbook? How much memory do they have?