Contrary to popular belief RAM (memory) does not actually speed up a computer. RAM however, allows you to keep more and larger files open at the same time.
The more RAM you have on a system the larger the installation will be. Windows7/8 normal install with 4Gig of RAM is about 28Gig, 8Gig of RAM 32Gigs, 16Gig of RAM 40Gig, 32Gig of RAM 54Gig, while if you go to 64gigs of RAM, Windows installation may exceed 100gigs. These numbers grow even more as you do windows updates.
In the below example we opened a Video file in Premier Pro CC and added a few filters such as Anti-Aliasing, Noise, Brightness & Contrast. We then rendered the file, firstly with 8 Gigs of RAM then 16 and finally 32 Gigs.
Render time with 8Gigs RAM : 10mins 53secs
Render time with 16Gigs RAM : 10mins 21secs
Render time with 32Gigs RAM : 10mins 13secs
As you can see the render time improved only marginally with more RAM.