You can also help the speed by clicking on the desktop anywhere, then in the Finder menu at the top, select Preferences, then click on Sidebar (at the top of that window), then uncheck "Connected servers" under SHARED. Then you may want to go back to General (still in Finder Preferences/top of window) and check "Connected Servers" (so that you know when you are connected and can get to them via an icon on your desktop).
You may also find improvement with the following commands:
sudo sysctl -w net.inet.tcp.delayed_ack=0
sudo sysctl -w net.inet.tcp.recvspace=40960
sudo sysctl -w net.inet.tcp.rfc1323=0
(note: the defaults for delayed_ack, recvspace, and rfc1323 are 3, 131072, and 1, respectively)