The ram generally does not clog, what usually slows a computer down is the type of hdd you have and startup programs. You can see what startup programs you are running by typing msconfig.exe in your run window/search bar depending on what version of windows you have and clicking on the startup tab. Take everything out you dont need. 

You can search for the program name in google to see what it is or does and its relevance to you.

A solid state drive is extremely fast, and I load windows 10 in about 7 seconds max. i would recommend one.

2gb of ram is more than enough.