Any extension is going to slow the network down. Your best bet is to use the split network feature to have a faster network (The 5.8ghz band is best for this), and an extended network (the 2.4ghz). Otherwise, maybe another extreme, or just run wired ethernet for the distant location, and then put the express on that wire. When you run a wireless extension, you're cutting your bandwidth in half, so you get distance at the cost of speed.