Macbooks accumulate a lot of dust during their life, and they're not really servicing-friendly. But many people reported lower temperatures die to better cooling.
This also means longer lasting batteries and faster CPUs (because of less thermal throttling).
It won't completely resurrect your MacBook, but it might give a significant performance boost (and lower the operating temperatures).
I agree on this. Re-pasting the cooler + clearing up the dust boosts the performance quite significantly. But beware that you need to pay attention to the rubber gasket and how it seals to the body. On the rMBP 2015 the camera cable needs to be clipped into the gasket carefully to maintain the seal.
I did opened the macbook several times to replace the disk, ram and the battery and I always clean the dust from the fan surface, but I never considered opening the fan and reapply the thermal paste. Maybe I'll do that later when I have some extended downtime.
Macbooks accumulate a lot of dust during their life, and they're not really servicing-friendly. But many people reported lower temperatures die to better cooling.
This also means longer lasting batteries and faster CPUs (because of less thermal throttling).
It won't completely resurrect your MacBook, but it might give a significant performance boost (and lower the operating temperatures).