Here's something that doesn't seem like it's affecting performance, but it's still very annoying if you need to look at your logs. I have a thread about it here:
https://forums.macrumors.com/showthread.php?p=4848292
Basically, running any Office app and I get tons of these errors in the console log:
Jan 28 15:49:57 computername Microsoft Excel[35241]: CGBitmapContextGetData: invalid context
Jan 28 15:49:58: --- last message repeated 29 times ---
Jan 28 15:49:58 computername Microsoft Word[35225]: CGBitmapContextGetData: invalid context
Jan 28 15:49:59: --- last message repeated 14 times ---
Jan 28 15:49:59 computername Microsoft Excel[35241]: CGBitmapContextGetData: invalid context
Jan 28 15:50:22: --- last message repeated 49 times ---
Jan 28 15:50:22 computername Microsoft Word[35225]: CGBitmapContextGetData: invalid context
Jan 28 15:50:30: --- last message repeated 100 times ---
Jan 28 15:50:30 computername Microsoft Excel[35241]: CGBitmapContextGetData: invalid context
Jan 28 15:51:00: --- last message repeated 189 times ---
Jan 28 15:51:00 computername Microsoft Excel[35241]: CGBitmapContextGetData: invalid context
Jan 28 15:51:14: --- last message repeated 59 times ---
Jan 28 15:51:14 computername Microsoft Word[35252]: CGBitmapContextGetData: invalid context
Jan 28 15:51:44: --- last message repeated 324 times ---
-Kevin