Latest Firefox version seems to use up a lot of computing capacity

[FredBln]

Hi, I updated to the latest Firefox version 148 today and since then my MacBook's ventilator is getting loud within a minute or so after starting Firefox, even without having loaded a website. Firefox seems to use a lot of processing power - looks as if there's something wrong with it. I run it on MacOS Monterey version 12.7.6

[FredBln]

Doesn't happen when I use the Safari browser