You might want to test whether or not the excess energy use is due to a problem with Safari itself, or with something else. (eg: interference / compatibility issues etc.)
Start up your Mac in safe mode - Apple Support
Eg: says: "If the issue doesn't continue in safe mode
Leave safe mode by restarting your Mac normally.
If the issue doesn't return, it may have been resolved by the other things that safe mode did at startup, such as checking your disk and clearing caches.
If the issue returns after restarting your Mac, it’s caused by a login item or other software that safe mode prevents from loading at startup. "
If the excessive use does not continue when in Safe mode, yet does return after leaving safe mode, then we need to look elsewhere than Safari for the solution.
(Eg: Downloading and running the free version of "Etrecheck", (software developed by a well-respected community member) can provide a long, detailed report on the situation. Best time to run it, is when the high energy use is occurring. The report contains no private details, and running it does not change anything.
The Etrecheck report can be "copied & pasted" into a reply window using the "additional text" icon (third icon from the right end of the row, under the reply window). Some community members here are well-skilled in interpreting the result and pin-pointing the cause of the problem.)
