OK, I did a search&test on SVN and have found out that rev 3548 makes harm for me (low speed). 3547 is OK.
BTW: To perform iterations faster I had to find out how to get results (good/slow speed) very fast. I've found out that while any driver can perform good right after it was loaded, fixing rate for low speed driver to 54M produces low speed. One can later set it to auto again, but speed will still be low.
For good driver, it is usually OK while fixed at 54M. At times it is not OK(rarely), one can set to auto to get regular 17-19Mb/s of iperf speed (I've had 3.5MB/s ~= 28Mb/s download speed at OpenSuse 10.3 before the upgrade, but it seems that this would be another reason search).

Note: all the tests are done from same place, usual statistics is:
Bit Rate=54 Mb/s Tx-Power:18 dBm Sensitivity=1/1 Link Quality=41/70 Signal level=-52 dBm Noise level=-93 dBm