Memory is more than likely the problem, but there may be other things you could do.
If your system came 'loaded' with programs they may activate when you start your computer.
I am assuming you are running a version of Windows.
If you look at the 'task bar' at the bottom of your screen, you will see little 'icons'. The ones on the left are 'quick links' to start programs. The ones on the right (beside your clock) are already running.
If you have too many on the right they may be choking your system.
On my system I only keep my anti-virus, my 'firewall', my clock (I don't think it takes much 'resources'), and some other stuff that I find 'cute'.
I have more memory than an elephant, but I still keep my system trim to keep the speed up.
See if you can figure out which stuff you need and which you don't.
There are other things you can do to improve 'performance' but without knowing your system it is hard to tell.