2010 macbook help!

So I think I need to upgrade my MacBook because recently I've been getting some awful lag. use firefox with 3-30ish tabs, steam (I shut it off when I'm not using it), skype, i message, notes, parallels 8(windows 2000), game capture hd, and Microsoft office suite. I would like to add the adobe cloud stuff but that for later. I have two ideas.

1: optimizing osx can I do this? I have a feeling its not quite like windows.

2:Upgrading I was thinking of ditching the dvd drive and throwing in two WD red 750gb or 1tb dirves and 16 gb of ram.

I'm I missing something to speed up my mac will new thermal past stop my spu from getting hot and thus not throttled? and would raid 0 be used across all os's I want to use windows or Ubuntu.