I've had some trouble getting good wifi performance out of my Pi, but after lots of googling and trying things I get about 2.5Mbit/s and a median ping of about 230ms.
Not great, but tolerable.
Except that the AVERAGE ping is over 1000ms, simply because every few minutes the wifi completely stalls for a few seconds, creating pings with up to 12000ms (but no package loss).
I've already added a seperate power supply to the wifi-dongle (with a USB Y cable) and added
options 8192cu rtw_power_mgnt=0 rtw_enusbss=0 to
/etc/modprobe.d/8192cu.conf which should disable the powersaving mode, but it seems the Pi still sends the dongle to sleep every so often.
What can I do to fix this?
EDIT: I confused MB and Mbit, oops ^^"
EDIT 2: lsusb output:
Bus 001 Device 005: ID 7392:7822 Edimax Technology Co., Ltd
EDIT 3/4: uname -a output:
Linux zehnvorne 4.1.7-v7+ #817 SMP PREEMPT Sat Sep 19 15:32:00 BST 2015 armv7l GNU/Linux