I have three Macs on the same LAN/Wifi at home (Airport Extreme), all running Mavericks 10.9.2. Two Mac Minis (bought 2013) copy files to/from each other over file sharing at an acceptable speed, e.g., takes 2-3 min to copy 2G data over WIFI.
However, the third is a Macbook Air 2012. When copying files between the Mac Minis to the MBA, it's extremely slow. For the same 2G data, it's about 1 hour over WIFI.
What's more strange: I restarted the MBA a couple of times just to see if things can improve. The first time when it restarted, the copying process estimated to 2 hours, and the second time 3 hours!
I tried many suggestions on this forum dealing with Mavericks' slow Finder and file transfering, none of which helped.
I think one logical conclusion I can reach is that there is something different between the MBA and the Minis. But I can't figure out where.
One of the Minis uses a fusion drive, and the other SSD. So I don't expect disk performance to be part of the problem.
Best Answer
Solved it myself.
The MBA was on a different WIFI connection (2.4GHz). The problem is gone after I switched the MBA to the 5GHz WIFI, which the other machines are connected to.