unreal is extremely slow on iMac

[zooby]

@marksatt-pitbull;172587

Good news! I have confirmed that the bug we were having to work around was fixed in 10.10 & so from 4.6 onward the Intel GPUs should see a significant performance increase when running on 10.10 and later. How much faster will depend on the scene complexity, but it should be noticeable in almost all cases.

10.10 what? What is 10.10? Is it the version of the driver? The version of the graphics card? The date 10th October? The version of Unreal? What is 10.10?