Were you using Boot Camp or something else? I actually develop Cosmoteer on a Mac using Boot Camp, and it runs great.
No, I used VirtualBox, I didn't really want to do boot camp, because it sounded a bit more extreme.... What kind of mac do you have? I have a 2014 macbook air, maybe you have an imac or something. Great to hear you're also a mac user! Also, I've been programming for about 8 months in javascript, java and now I'm starting game development in unity (C#) and I was wondering how long it took you to make Cosmoteer so far (It's such a high quality game), that also includes making then engine. (sorry if you already answered this on the FAQ).
Yeah, VirtualBox performance is really bad, I definitely don't recommend it. Boot Camp will be the best since it's not running on a VM, but even Parallels would probably be better than VirtualBox.
I use a 2015 Macbook Pro.
I've been working on it full-time for pretty close to 2 years now, and it existed as a side project for several years before that.