Hi Gavin - yes, I've done that, no difference. I'm also using Xojo on three different Macs as well, all exhibit the same performance issues. 2016 MacBook Pro max specs, 2014 iMac 5K max specs, and 2012 MacBook Air max specs.
Just to clarify — you're not seeing any lag whatsoever when clicking on controls or dragging items around in the GUI editor of the Xojo IDE? That is strange. I'm not sure what else I can try. I am working with pretty big projects, though nothing massive.
I had said earlier I was having these issues on blank brand new Xojo projects — that seems to have improved. Dragging is more responsive, though not instant as I had seen in REAL Studio. But whenever I'm working in an existing project, it slows down noticeably — especially on windows with pagepanels and tab views (which my apps use quite a bit). Dragging especially is very cumbersome.
My projects were always lightening fast when working with them in REAL Studio 2010. Never saw any noticeable lag.