I know this is a bit vague, but I've had a repeating random problem for months where my whole desktop would hang for about 5-10 seconds over and over. Sometimes I would go days/weeks without any issues but sometimes I couldn't go hours. Once it started doing it the only solution I could find was to restart my computer.
I finally sat down and tried to trace the source of the problem and realized once it started hanging it would then hang every time I pressed the shift key. This allowed me to reproduce the problem consistently enough to find the source in Console.app.
When pressing the shift key these errors would be shown
|error|14:47:18.067894 -0800|hidd|:Event enqueue error:0xe00002e8 type:17 sender:0x1000106d5|
|error|14:47:27.727804 -0800|BetterTouchTool|Fail to get parameter with status 0xe00002d8|
|error|14:47:27.730485 -0800|BetterTouchTool|Fail to get parameter with status 0xe00002d8|
|error|14:47:27.733154 -0800|BetterTouchTool|Fail to set parameter with status 0xe00002c7|
|error|14:47:27.734725 -0800|BetterTouchTool|Fail to set parameter with status 0xe00002c7|
|error|14:47:27.804893 -0800|BetterTouchTool|*** not expecting invalidation break on '_CFMachPortDeallocationFailure' to debug: {null - ic:0,ip:354067}|
|error|14:47:28.303777 -0800|hidd|: Event enqueue dropped:333 consecutive events|
I'm not a wizard so this is all gibberish to me, but I figured it was related to BTT. When I closed BTT the computer no longer hangs when when pressing the shift key and after relaunching BTT it still works just fine (for now) and the errors no longer appear in my console. I'm sure it will do it again, but at least now I know to relaunch BTT instead of restarting my computer.
My Specs are
MacBook Pro (13-inch, 2017, Two Thunderbolt 3 ports)
Processor 2.5 GHz Intel Core i7
Memory 16 GB 2133 MHz LPDDR3
Graphics Intel Iris Plus Graphics 640 1536 MB
OS Mojave 10.14.2 (but I'm pretty sure the problem started quite a while before I switched to Mojave)
I understand that it might be something else that is broken, but I was excited to track it down to this and I don't know enough to go any farther.