Cursor flickering when changing cursor type to pointer

Macbook Pro 13" Early 2015 on High Sierra 10.13.4

Hard to describe this issue - whenever my cursor is *not* the default pointer (when it's the hand or the input cursor etc) and it changes back to the default arrow pointer, it "jumps" about a cursor-width to the left for a couple frames and then goes back to where it's supposed to be. it doesn't cause any issues, it's just super irritating.

This only happens on my external samsung s27c750p monitor, on my laptop screen it's normal.

any information would be greatly appreciated