Hi Michael,

The slight lag is apparent as soon as I initialise the creation of any object (curve or solid) by left-clicking once in the viewport and then moving the pen to determine the size.

It happens at any time, also when I've just started a fresh scene. It might be an AMD-specific issue, as I've recently switched to a new iMac. Previously I had an iMac containing an NVidia graphics card. I don't know if you're using OpenCL. I've heard MacOS support for OpenCL is crappy compared to their Metal support.