Brave (with ~40 tabs open) typically consumes the most CPU cycles of any process on my (W-10) machine. Improvement is ‘desperately’ needed, perhaps ‘background’ tabs could suspend their threads until reactivated (brought to the ‘front’)? I have hundreds of tabs open in Chrome, but Brave still manages to ‘beat’ Chrome as the top CPU user.
Try using the Tiny Suspender extension, perhaps, like I do?