Incredibly high CPU on Lightroom Classic

As @johnrellis has replied, the high CPU useage, spinning fans and high temperature are normal with later Intel based Mac's. Sadly, the 16-inch 2019 model is an extreme example, and gets horribly noisy with jet engine fans when used with an external monitor.  At 233 pages, this thread on Macrumors indicates the scale of the issue  https://forums.macrumors.com/threads/2019-16-is-hot-noisy-with-an-external-monitor.2211747/  Even running without an external monitor the fans will roar up to max when building previews or exporting images. 

BTW, other than the GPU having 4GB of VRAM, I have the same spec as yourself. However, since I bought the 16-inch M1 Pro MBP I use the 2019 MBP for running Windows apps.

"I was exporting a few files, and the CPU is jumping to over 1.500 % something I have not seen before. "

That's normal for export -- LR tries to use about 85 - 90% of your total CPU while exporting. Your computer has 8 cores (16 virtual processors), so Activity Monitor will report a maximum of 1600%.  I have a very similar 2019 Macbook Pro, and CPU is steadily at 1500% during an export.  (Rendering raw photos is very CPU-intensive.)

"After a while it would always slow down and I had to restart it as the macbook was getting really hot."

Many Apple laptops, including the Macbook Pro, are designed to run hot, with noisy fans, when you actually use their CPUs to the fullest (which most apps don't do):

https://support.apple.com/en-us/HT202179 

However, if your Macbook is noticeably slowing down, then it's very possible that the fan vents are clogged with dust or there's something else wrong with the fans.  When the CPUs start truly overheating, Mac OS (and the firmware in the processors) will slow down their clock frequency to let them cool.  The free Intel Power Gadget will tell you quickly whether that's happening on your computer:

https://www.intel.com/content/www/us/en/developer/articles/tool/power-gadget.html

If it is, and trying to clear the fan vents doesn't help, take it to Apple to get serviced.

Have you just updated to LrC 11.3.1? That version may be buggy for some MAC users, Especially if M1. Some find rolling back helps.

3. Things running in LrC that are eating resources

Are any odd options in LrC running. Specifically Face Recognition, Address Lookup, Sync to Cloud.

Is a long (in time to complete) import occuring

2. MACBook power source

Are you running plugged in or on battery?

1. Sys Info

Please post your System Information as Lightroom Classic (LrC) reports it. In LrC click on Help, then System Info, then Copy. Paste that information into a reply. Please present all information from first line down to and including Plug-in Info. Info after Plug-in info can be cut as that is just so much dead space to us non-Techs.