Repasting a MacBook

If you have any of the Air models which lack fans, there's a common hack of putting thermal pads between the CPU heatspreader and case, effectively turning the bottom case into a large heatsink, and giving your system a longer maximum performance before throttling.

The downsides is that this makes the bottom of the case quite hot on a place you can touch, but putting a plastic hardshell over the entire laptop deals with that, and also gives protection.

Making the bottom case a heatsink and then putting a plastic insulator around it seems to defeat the purpose of the whole attempt?

It's pulling the heat away from a concentrated region into a larger region.

Performance numbers reflect the optimization. I personally haven't done it for fear of affecting the battery lifespan (and possibly other components' lifespans.)

Really hard to resist due to its simplicity and noticeable improvements.

I can't say I am tempted. When I played a game on an M1 Air, the underside became unbearably/worryingly hot anyway. I accept it's not for sustained load.

I still have pads left over from trying my damnedest to reduce fan noise on a Dell XPS. Used pads on every hot stop and didn't help.