I have a MacBook Air, and using an Airport Extreme Router (802.11n 5GHz mode only), to transfer a 4GB file, Finder says it will take 28 hours! It just stalls after 10MB or so. I have all the latest updates (10.5.5 and all firmware updates for the router and MacBook Air). I have also tried a clean install and it's still the same problem. On my MacBook Pro, the same file took less than 6 minutes to transfer (which is how it should actually be for 802.11n)! So it is definitely not the router or the other computer than has the file being transferred. I was wondering if the MacBook Air wireless is truly this bad, or is there some kind of solution or workaround. If it is this bad, this is truly unacceptable for a laptop that was advertised for its wireless capabilities. Thanks EDIT: It is not the wireless chipset (Broadcom BCM4321) because I use the exact same chipset in another mac, and the performance it what it should be...around 6 min or so to transfer the file. UPDATE: I think I have found the issue...I copied the IO80211Family.kext from a 10.5.2 machine onto my MacBook Air, and the transfers now take 8 min for the 4GB file! This is more like what I was expecting. Looks like it had to do something with the 10.5.5 network drivers.