So I am dealing with an issue here with BP Actors that have variable arrays (In our case it is an array of transforms) that have many thousands of items. If this variable is marked as “Editable” so that it shows up in the properties panel, then perf takes a serious hit. Make the variable not “Editable” and perf goes back to normal. After some digging through stats it appears as though the problem is in Slate. Specifically the “DrawWindows” under the Slate STAT jumps up to very high times. Now my guess is that this is time spent drawing out all the UI controls for the very large array.
However this perf hit is there even if the control is “collpased”, and even if the parent control is collapsed, therefore the variable isn’t even visible. My guess is slate is computing and drawing this even when it isn’t necessary.
EDIT: Had the name of the slate command wrong. Fixed. It is DrawWindows