Compressor 4.1.2 slowing down my computer until it is unusable

Hey all,

I'm using an iMac (specs below) and I have the latest versions of FCPX and Compressor (4.1.2). I've had a HUGE number of issues with the new Compressor update, specifically when it comes to 4K video. I'll take a project that is in 4K, OR that I shot in 4K and downscaled to 1080p by making the FCPX Project specs 1080p, then I "Send to Compressor."

Then I try to export from Compressor using default 1080p settings to my desktop.

Previous versions of Compressor would take their time in giving me my final project, but would otherwise leave my computer unaffected. However, Compressor 4.1.2 is slowing down my computer to the point where it is unusable. Moving windows/folders around on the desktop takes forever to load. I can't browse the internet or do ANYTHING when Compressor is doing its thing now.

Interestingly, when I export using FCPX's "share" function, I have no problems.

Help! Is there anything I can do with Compressor to stop it from destroying my computer memory every time I export something in 1080p from 4K? Is anyone experiencing the same problems?

Thanks!

Specs:

iMac: 3.4 GHz Intel Core i7

16 GB 1600 MHz DDR3

NVIDIA GeForce GTX 680MX 2048MB