I've been running a 4GB ROM DAW forever and never have any issues.

Of course, more is better in 99% of the cases.

One of the biggest improvements in performance I have seen came from an upgraded processor.

Going from my duo core chip in the Dell lappy ( I think that lappy was 2GB ROM)to the Intel i5 quad core with a higher speed made a huge improvement.

In the lappy, I was running projects in Sonar that were pushing the processor to 75% and that would result in some issues on playback. Especially if I had some of the memory hog plug ins running in real time. Ozone and Melodyne in multiple tracks with several synths and a bunch of audio tracks would do that.

Once I got the i5 quad running, that same project dropped back to below 25% on the processor.

All that said, I think the speed of the processor has a larger influence on performance. Memory does play a part as well so the computer has room to swap things around as needed.

You can find my music at:
www.herbhartley.com
Add nothing that adds nothing to the music.
You can make excuses or you can make progress but not both.

The magic you are looking for is in the work you are avoiding.