I'm using IDEA (2018.x) on both Windows and Mac. This isn't really an IDEA specific question but it may be a community where people have good ideas and answers ;-)
Mostly I build on a 2016 MacBook Pro 15". I mostly work with some open source projects and my typical build for one of these takes 5-6 minutes on the mac. It's a fair size project, and I'm very happy with this. IDEA is also very responsive. I'm using maven 3.5.3 & java 1.8 (162)
If I build on windows 10 (with idea directories excluded from AV) the identical build (there aren't any platform specific build changes)I get 15-20 minutes. That's on a pretty decent few years old i7 4 core/16GB ram/SSD system. Building on my i5/4GB/SSD Surface pro 2017 the build is taking 25-30 minutes. No surprises it's slower of course. Crystalmark disk I/O performance checks seem fine, and I've noticed no other issues with other tasks
If I run the build under an ubuntu vm on that same windows hw (Hyper-V enabled) I get a build time more like 7 minutes... no surprise as the hardware isn't that different to the mac in overall performance
I'm a little bemused why mac >> windows. At least on the desktop I see no evidence of memory constraint/paging or the intellij process suffering.. disk I.O is significant, not 100%, cpu is way down - but then these are all multicore systems. I can only conclude that perhaps it's the file system/ntfs just being less efficient than Linux file system, though it could also be the java vm.
As I said not really intellij, but perhaps people with experience of crossplatform dev could comment?