So I want to make sure I’m understanding correctly: using safari and safari ONLY is when you fans heat up? And it doesn’t do it in chrome at all? Or any other browser? I’d honestly suggest transferring all of your safari data into google chrome in that case. Better Adblock support, better integration for apps, etc. is there any particular reason you’re stuck with safari? Ease of use/familiarity? If so, I’d look into these options to fix it, ESPECIALLY cleaning your fans if you don’t do so regularly. It may take a few specific screws from iFixIt, but it’s well worth the speed boost and peace of mind knowing your computer will last longer.
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Why is my Mac fan so loud? Causes, troubleshooting and how to get it to quiet down
When your computer overheats, your MacBook's fan kicks into action. But when it runs too long or too loud, there may be another cause to consider.