Hi guys,
Thanks very much for all the responses. My 2012 MBP looks like a new powerful machine after I upgraded it with 16gb RAM yesterday.
I also opened the same PT project I used to run with 8gb (a feature doc with +30 tracks, plugins and video) in which the disk usage window was saying that Memory was around 75%~ and now is always less than 37%~, so that's good news
Thanks again!
Javi