I have an ac66u_b1 with 384.8_2 firmware. The web UI is painfully slow when using firefox or chrome; pages can take 10 to 20 seconds to load. For whatever reason IE is quick and has no problem with the merlin firmware. The official asus firmware doesn't have this problem at all. I've tried factory default settings in the firmware, tried unloading all browser addons. My computer, running win7-64, is a little old so on newer PCs it might be less noticeable.