In my experience, the only time the LR database slows things down is when you have a lot of images in it and you back the catalog up at shutdown. The backup process has to go through the entire catalog and check for errors so it takes longer to complete the verification and backup. However, you can just walk away and let the backup proceed. You don't need to do anything while it's happening and you can go on to other tasks on your computer so it really doesn't impact you.

While using LR, the database is just as fast as your computer can manage. Computers do tend to slow down with age since they accumulate more background processes that steal CPU time.

This has been my experience, too. I will note that the latest version for Macs does use SIGNIFICANT energy. My M1 MacBook Air never drains its battery very quickly unless I'm using Lightroom Classic. Two nights ago, I went from 100% down to 20% in less than five hours. The Activity Monitor app showed that LrC was using 30% of the energy, Safari was using about 13%, and the rest was used by dozens and dozens of other things. (When not using LrC, I can get 10-13 hours of light work out of this thing on battery, and it never slows down...)

Rolling on the floor laughing!

Point taken. Real photographers use whatever the hell they want to that makes an image. The point isn't the medium, it's the message! The medium may shape the message a bit, but the message of a photograph is the image it portrays.

See attached example. The Tri-X film original was (re-)processed in Negative Lab Pro and Lightroom, then updated to hideous with Photoshop Neural Filters. The message is the same, but the weird cold colors and painterly, almost "underwater" effect enhance it.