I'm been working (5 years) on a long hall documentary film in PPro 2014.2 on OSX 10.8.5. Early 2013 Macbook Pro (16GB RAM). Lacie TB JBOD Enclosure.
The project actually started on CS6 and when I transitioned from CS6 to CC the project went from 550MB to 50MB in size.
Recently I've been experiencing what I believe is a situation where, after having the project open for a while, PPro seems to start taxing the system in the background. The Macbook's fans start kicking in more that usual... and even opening a browser window to the internet (without any heavy video or graphics) can easily kick the fans into high gear even while PPro is just sitting idle.
I'm running an external Dell U2711 monitor via HDMI. Sometimes I wonder if resizing PPro (and Microsoft Word doc) windows in this monitor triggers the bug.
I've been trying to research what the problem is, I hear things like memory leak etc.
When I open Activity Monitor, I'm not really sure what the % of CPU and Memory usage should be under normal operation so don't really know where the problem could be.
Sometimes when I save the project and quit, PPro will save but won't close (requires a Force Quit). During this time (save/ quit) it will not letting go of the Media Cache Folder located on an external drive - however the other drives containing media will eject.
When the system - with PPro running - goes into a 'situation' where it is being taxed, restarting the Macbook and reloading PPro fixes the problem, for a while. But It takes 20 min to load and index the entire project.
I'm wondering about upgrading the OSX and moving the PPro project to 2015.3 but hear that it is not wise to upgrade in the middle of a large project but this issue is getting annoying and I will be editing for 18 months more. But I wonder if I would be just trading one set of 'bugs' for another with the upgrade to 2015.3, though I'be been reading that it can be better than the more current versions.
I'm really in the thick of it here with this monster of a project that has taken the better part of 5 years to build... I could really use some sound advice.
The short answer to your question is you need more RAM, but since you're on a MacBook Pro, you can't get more than what you already have so you'll need a newer computer (iMac or MacPro) that can handle 32GB of RAM or more (personally I would opt for 64, in which case I believe only the most recent versions of the iMac support 64GB and only if you make the purchase through OWC (macsales.com)).