As for now the CPU is loaded 100% when generating thumbnails/previews/100% prevews in cache.
A lot of people report the same problem!
Please speed up the the process that makes 100% previews in cache.
As it will probably not be speedy even after that, please provide a tool for preparing 100% previews in local cache on scratch SSD drive (no copy in photo folder (useless for single users) - at least it should be an option).
It should be possible to select preview generation for af folder and optionally selected or all subfolders.
When the proposed tool becomes available it will be possible to prepare a lot of 100% previews overnight!
I am really looking forward to that, as a lot of time is waisted while waiting as it is is today.
Update: Obviously the generated 100% previews should be stored i cache until the cache is purged!