Earlier quoted context omitted.
I use a mac alongside a win10 machine, with the win10 being brand new i7 hardware with ddr4 ram. And OSX's UI is far far snappier and hangs quite a bit less. My win10 machine often will just hang for no reason at all for a few seconds, then pop up whatever I had switched to.
Which GPU are you using? I have a 2015 Mac Pro with two D500, before I had a mid tear iMac. The mac pro stands directly besides my "beast" a i7 6700, titan x, nvm custom machine. I can't really describe it, but it's bothering me and I would put my hand in a fire betting that it's somehow measurable. It feels like the input lag of a cheap IPS-Monitor. Every klick, every slide, every window resize has this minimum lag…
On my beast Win10 machine, everything is also instant, it's just randomly throughout the day, it will lock up while tabbing to an app or something for 10 seconds.....which is just so weird and annoying. CPU shows it is pegging a thread for the opening app, doing who knows what.
My mac is a 2013 MBP with a intel 5200hd.