Hi, So yes, as in the topic. If your MacBook is running slow from time to time, clean them. In OS X under heavy load my mouse cursor tend to slow down and kernel process went over 100%. In Bootcamp Windows 10 under heavy load, MacBook was switching off (guess to prevent damage). It's a MacBook Pro 15" 2011, with updated RAM to 16gb. Unscrew bottom bit and unscrew the vents (without disconnecting the little vents power cable). And clean the air tunnels, you'll see them after lifting the vents. I've missed it when cleaning my MacBook before. And what a difference it makes ! Please see "how to" online and be careful when cleaning. Hope it helps someone.