My first post here. Problems concerning iMac 18,3 / High Sierra / Parallels 13 / Windows 7 After my Mac Pro 3,1 died, I chose a new iMac with Fusion Drive. Big mistake! I should have taken the SSD version. After the migration procedure Parallels 12 was slow, I upgraded to Parallels 13 and Win 7 was even slower, unusable. For months I was screening the www for a solution, nothing helped. Not one of the ideas in this thread! A few days ago I saw this hint with the Fusion Drive, cloned High Sierra to an external Samsung T5 (SSD with USB 3.1 via Thunderbolt 3) -> Startup was slower than with Fusion Drive, but Win 7 was running as perfect as expected. My permanent solution is the following: I copied "Windows 7.pvm" to an old Intel SSD (250GB in an external Icy Box in my case), moved the original from the Fusion Drive to the trash, defined the new path and now I am happy again.