Experiencing the same issue. I’ve used Brave across multiple platforms over the last year and haven’t noticed this before (though perhaps I just didn’t notice).
Mac Os Sierra, 2017 model 2.8Ghz / 16 GB memory .
I was wondering why my fan was roaring all day today. Checked out activity monitor . THe Brave Browser Helper (Renderer) was using close to 100% cpu. I don’t have that many tabs open, so it appears more particular pages cause the cpu usage to spec due to some rendering stuff. In any case, big fan of browser and BAT but can’t use this version currently due to this.