I've used Mac for 8 years (since the 1st gen Intel MacBook) but now I really want to run away. My current Mac is a server-level 2013 i7 Mac Mini with 8G RAM. It's not uncommon for me to run Mail, SubLime Text, IntelliJ IDEA and one or two VirtualBox guests on it, and then CPU goes high, the whole machine slows down, and fan produces loud noises. On the other hand, my ThinkPad running Windows 8.1 with a similar hardware spec can handle them smoothly. I agree Mac is more developer friendly than Windows, but doing daily developing work with cygwin/SubLime Text/IntelliJ IDEA is almost identical on both platforms. I admit I'll try installing Linux if I make the decision to switch to the ThinkPad as my main desktop.
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.
