Try scrolling a facebook page on a MBP :) The fans are pretty at max.

What? I'm writing this on a late 2008 MacBook Pro(yes, one with a 2.4GHz Core2Duo and 4GB of ram!), running latest Chrome and the fan might as well be off - if it's running, I genuinely can't hear it. I also have a 2012 MacBook Air, and the only time when I could hear the fan on that was when I foolishly tried playing Guild Wars 2.

I just spent 60 seconds scrolling up and down on Facebook like a madman, no issues.

This is with Safari though which easily has the best UI performance out of all the browsers.

Wat? You must have one of those entry-level models with 4gb of ram. My 2012 mbpr never starts fans unless the gpu is taxed.

Early 2015, 16 GB RAM.

I had a late-2015, 16GB of RAM mbp, and it also would spin up pretty high and get noisy, especially when using Google Chrome. It would also have some kernel thread crash during suspend, causing it to come on in my bag and get extremely hot.

A complete reinstallation of the OS via a USB installer seemed to mostly solve the issues somewhat, seemingly making the crashes mostly stop and the heat/fan profile more "normal" (just stumbled upon this). I guess I suspect ACPI weirdness...

Friend has similar behavior on his older MBP. Turns out all the vents between the keyboard and the display (directly adjacent to the hinge) were filled with dust.

I really suspect theirs are caked with dust, because Macs will sooner downclock their CPUs massively rather than spin the fans up during normal use.

Something is very wrong with it.

Maybe Firefox and all those auto-playing videos.

Macs also thermal throttle a lot. Apple opts for quieter machines over exposing the entire raw power of the CPU like a lot of their competitors do.

In large part because Jobs had a pathological hatred for fans. The Apple II used to have problems with thermal buckling of the logic board because Jobs insisted on there being no fans. And the later Mac Cube ran into similar problems (never mind that oversensitive capacitive power switch).

Macs are also notorious for running hot.

Tell that to my MBA late 2010 since Maverick

Like I said above - I have a late 2008 MBP running latest chrome + El Capitan and I've literally never heard the fan on that machine - and I use it daily.

And I have a 2010 MBA and I hear it every day.

Don't forget IntelliJ.