I run a Mid 2012 13inch Macbook Pro, I used it everyday in the last 10 years it's a great machine.
I never had the problem you describe but the first thing I would do if to format the system hardrive and do a fresh MacOS install.
I'm on Pro Tools 10 so I use 10.9.5 Mavericks on my machine, you have PT11 so just download from the web the last OS that works well with PT11. You can find the download links for the different OS in Torrent sites, if you need help for that send me a PM. As you need an older MacOS version probably is not available from the Apple store so you need to get it from a third party.
So do a fresh install and see if that solves it.
I hope it will because once you use a MAC you are not ever going back to a PC, I was a PC/Windows user for 22 years until I got my first Macbook and couldn't believe how simple life could be.