Qcrypto, I personally use Brave in combination with Firefox (often at the same time) and here I just looked at the data that says that 2 open browsers and a total of 5 tabs have a consumption of 77% RAM and 7% CPU (my total RAM is 8 GB).

I did a little research on why things like this happen, although the main cause is too little RAM in relation to the needs, at some point you can try to fix the thing by turning off Hardware Acceleration or Increase The Page Filling - see more information at the following link :

https://techviral.net/not-enough-memory-to-open-this-page/