Thanks, cnimi.
Would you mind trying one more set of commands? In terminal, sudo apt install htop and then htop. This one will show you a more complete list of processes. So, for instance, you may see a whole bunch of “/…/firefox” or something like that. Can you identify the highest group? For example, if there are a whole bunch of firefox processes typically coming up high. This will also change the output, so it will come down to your eyeballing the output and giving me your best guess of what group of processes typically come up high. We have to identify at least one process that is consistently high, otherwise there is not much we can do.
Finally, could you also make sure your Software Updater settings are similar to the pics I posted here? Installing Samsung printer and scanner driver
If not, then please change as in those pics and then run the Updater and install any new updates.