:
Which version of UE4 were you working on? I do my daily work on a 2013 , but my night and weekend work on a 2014 , and I haven’t had the kinds of issues you’re reporting. In the early days of UE4, using the editor on the Mac was really rough, and most of my team would Bootcamp to use UE4. Since about 4.4, however, things have been much better, especially when combined with Yosemite. I actually removed UE4 from my Bootcamp partition.
Are you using spindle drives or SSDs for it? Any chance you’re hosting the project file on a non-boot drive? I have noticed with some of the energy saving features added with mavericks (or maybe earlier), it tends to put drives to sleep whenever it can. When a drive spins down, there’s a definite hiccup when the machine goes to access that drive, as it has to spin up to speed before it can start reading.
You might want to look at the energy savings settings and turn off the “Put hard disks to sleep when possible” setting. That’s the only thing I can think of that might be your problem. I’ve used UE4 on four different Macs (including a 2010 that’s probably comparable to yours) and haven’t seen this issue.
Wish I could be more helpful, but I just haven’t seen this myself, and nobody on my team has reported it either.
One thing to point out, though - I believe currently, with UE4, you have to have a Windows machine to generate a Windows executable, and a Linux machine to generate a Linux executable. While cross-compiling is certainly technically possible (Unity does it), I haven’t see anything from Epic about it, so I wouldn’t count on it.