Regarding the fans, there are many threads on this, and this appears to be the desired behavior according to Apple when the CPU heats up (because if the fans didn't do this, the CPU would overheat and the MacBook would shut down).
Regarding LR CC running so slow, please clarify:
LR Classic CC - sorry.
Everything was running ridiculously slow - I optimized my catalog, purged the cache, increased the max size GB for camera raw and seems to be working again.
THANKS for replying !