Unable to post in bug forum, please move there.
I used some live clay and made detailed sculpt area, then use Copy Clay tool to sample and apply elsewhere on the mesh, I noticed that once I sampled this data 3D Coat become quite laggy/stuttering on Intel skylake i5-6500(quadcore 3.2GHz 4 cores/threads). While bit difficult due to very low FPS, if I navigate mouse to tool options and clear data the CPU usage for Coat dropped down from 70% to 10-15%. I also tried hide the layer, no effect. It turns out that Blend being enabled caused the high CPU load, if disabled, CPU usage is still higher(averaging about 20-25%), clear data will be equivalent of changing tool which brings CPU usage back to normal(unless return to the tool).
When changing tools sometimes I noticed the sampled mesh data appear in grey like when using import or primitives tool. I imagine while it is not visible when using the tool, perhaps 3DC is interactively moving this mesh around still, so the denser the mesh data sampled, the more intense on the CPU? Any reason to do this, if there is no interactive preview, then perhaps the tool should not have high CPU usage doing whatever it is doing non-stop and just apply when user clicks? I imagine the CPU usage is higher for blend enabled because it's interactively blending in advance before applying when clicked?
The brush only seems to apply by single click, not applying multiple instances along a brush stroke, so it seems like this is a bug to me.