Welcome, aroooo, to Apple Support Communities!
There have been many discussions of this high Energy use (and fast battery discharge) issue, around here. So, you are not alone!
We recognize that this is especially troubling to MacBook users, since battery use is so important on such!
This is what is well known, by those of us that are “old timers”:
- Unless a computer has a hardware fault (such as a short-circuit, including an internal short in a battery), there is no way for a computer to use a great deal of energy without running programs being the cause! (CPU or GPU intensive processes, usually.) Of course, we all hope your computer’s hardware is and keeps running well!
- Big Sur is a major Operating System (OS) upgrade. It is not a mere update! In fact, Apple considers it to be such a major upgrade that they actually increased the major version number, from 10 to 11, for the first time since 2001!
- With any major OS upgrade, there are a number of “housekeeping” processes that run in the background (you won’t see them in Activity Monitor unless you change the View from the default of “My Processes” to “All Processes”): these are indexing all the files on your Data drive, analyzing and indexing all your photos/videos/music/books/etc., and any number of other “housekeeping” tasks to get the system ready for your daily use and convenience. (The results help make your system more responsive to your needs.) These will “settle down” when they have completed their “housekeeping” to the point that they are “caught up” with your files and such. (After that, just as with the previous OSs, they simply work as needed to keep up with what you change and add.)
- There are third party programs, utilities, extensions, etc., that simply may not be ready for such a major OS upgrade: they can get “confused”, and can “run amuck”, on your system, until you upgrade these third party programs! Please be aware of this potential issue. (With such a major OS upgrade, I’m, frankly, quite surprised we aren’t seeing more issues in this incompatible software category!)
You can run Activity Monitor, with the View set to All Processes to see what is running on your system, and how much CPU or GPU or Energy they are using. (Note: it appears that not all background processes have been “instrumented” for Energy use. So, the listing of All Processes using significant Energy is likely incomplete. However, since the majority of Energy use is generally due to CPU and GPU use, these will show up under the CPU tab, in Activity Monitor. That being said, though, the total Energy Impact is not dependent upon having all programs “instrumented” for Energy use.)
The Activity Monitor is a good tool for seeing what is going on “under the hood” of your computer.
Any time you wonder what might be going on, on you computer, that might be affecting its responsiveness, Energy use, Heating, etc.; the Activity Monitor can, usually, help you get an idea of what is going on.
(Unfortunately, if your computer has hardware faults, Activity Monitor is not the best tool for recognizing such issues.)
