The game thread was starting to stall quite a lot at 18+ tiles i thought even in a packaged build it would still be noticeable but i will check and let you know, maybe its fine. I have added in extra checks to stop things like diagonal movement through 2 other units so perhaps thats making it worse. Moving multiple units at once is more of a future thing i am expecting problems with.
Would love to see your C++ versions of expensive functions, i would certainly be using them to save where ever i can. Think i will still want to keep a BP only project and add the C++ functions in via a plugin though im not sure how sensible that is.