[e1g]

It could be that something within your OSX is not quite right.

My primary machine is a 2013 MBA, and I always switch between IntelliJ, couple vmboxes, spotify, 5-10 Chrome tabs, Pages/Numbers, and Skype. Often, I also run VMWare with Windows. My MBA never makes a squeak, and the only time I feel underpowered is when I have to open all of this at once.

Your hardware runs circles around mine, and should not struggles with such a basic workload - I would look into potential problems on the OS level or start afresh.