Q: HOw can I improve Internet performance on my MacAir

Hi...

Avoid MacKeeper >  Do not install MacKeeper: Apple Support Communities

Avoid third party cleaning utillities on a Mac. Your Mac runs maintenance in the background for you > Mac OS X: About background maintenance tasks

Internet performance? Slower? Check your downloads speed here > Speedtest.net by Ookla - The Global Broadband Speed Test

Less than 15Mbps download speed, contact your ISP for upgrade options for faster internet service.

Message was edited by: CS

Peggy ~ Welcome to the Support Communities. This article has some suggestions:

Mac troubleshooting: What to do when your computer is too slow

...Found by doing THIS.

"MacKeeper" is a scam.

If network performance is slowing down on two different computers at the same time, then it's almost certainly a problem with your router or your ISP.