A few days ago I bought a new tiny WLAN RT5370 USB Dongle (USB-ID 148f:5370) for my second Pi http://www.logilink.eu/showproduct/WL0084B.htm
. Like mentioned on http://elinux.org/RPi_VerifiedPeriphera ... i_Adapters
the installation of the dongle is quite easy. After updating the wpa_supplicant.conf with the details of my network, everything worked fine I thought. But then I figured out that communication over the wlan device is very slow and laggy. A common ICMP packet needs 200 ms to travel between my client and the Pi. Even a ssh session is very unpleasant slow. Where my other Pi with a different WLAN-Dongle needs only around 7 ms for an ICMP-Packet.
If I put the dongle into my laptop it works very fine. The funny thing is, if I ping from the Pi to any client-device there is no delay. On the other hand, if I ping from any client to the Pi there is this bad delay.
As a power source I use a 5V/5A max. industry power supply which powers the Pi and the USB-Hub directly. I'm using the latest Raspian version freshly updated (24.05.2013). I also tried two different Pi's. One revision 1 and oner revision 2 of the Modell B Pi.
I have no idea how to fix this problem... I will be happy about any suggestions.