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FF has a safe mode option that turns all the extensions off.
Sometimes extensions are the problem and not FF.
If the fan doesn't go nuts in safe mode, it's a fair bet, one or more of your extensions are involved.
Also, FF can still be something of a memory hog; but, more systems have plenty of RAM these days; so, that's not much of an issue anymore.

If you have an older system, with less RAM, run Chrome on it.

If you have a newer system with more RAM, FF's features are worth the memory usage.