Last year my MacBook started having very, very slow WiFi connectivity. So slow, in fact, I almost abandoned the thing. My wife’s MacBook was fine. But my WiFi connection just crawled. Then I read about some MacBook Pros, the new ones with the metal case, having a similar problem.
I was sitting right next to our WiFi router getting super slow connectivity. So I decided to remove the transparent plastic case I’d bought for the machine. It sure did look cool.
As soon as I removed the case (which is made specifically for MacBooks and costs about $30), my WiFi connection improved by about 1000%. In fact, it became normal. No more problem.
So if you have a plastic case on your MacBook, and your WiFi sucks, take the case off. Amazingly, 2 millimeters of plastic is enough to ruin your signal.