[SOLVED] WIFI slow - degraded performance

[nemke]

Software
XBian version: 1.0Beta2
XBMC version: 12.2
Overclock settings: 950MHz

Hardware
Power supply rating: Apple USB (5V)
RPi model (model A/B 256mb/512mb): Model B 512mb
SD card size and make/type: Lexar 8GB Class 10
Network (wireless or LAN): WIFI ADAFRUIT INDUSTRIES 814 MINIATURE WIFI MODULE, RASPBERRY PI
Connected devices (TV, USB, network storage, etc.): USB Keyboard, Monitor (1080p), USB WIFI Dongle

Logile
Link to logfile(s): N/A

Problem description:
Hi everyone, this is my first post. I've searched extensively and can't find the solution to my issue.

The problem is that my WIFI speed is very low. I am sitting 3 meters from the router. I am only getting 100kb/s - 200 kb/s on both read and write to the SD card (I am testing speed through WinSCP). I've tried different SD card, power adapter without any luck. Also tried OpenElec but I like Xbain more (same issue).

Wired works fine with no lag.

What can I try to improve the transfer speed?