Hi Mixx,
I tried to reproduce that and did this test again with a fresh 1.4.15 /WebDAV installation on a really bad equipped win10pro/64 notebook (i5-4310M, 8RAM)
The result was the same… My CPU Usage with this cryptomator version was nearly permanently 0% within my 1 minute staring at the task manager (now and then there was a 0.x% “peak”). Vault was open.
So, unfortunately I cannot reproduce this and please excuse for asking: are you sure that no other process is accessing the files in your vault, or your vault?