Your English is fine, but your typing could use some work
I'm not sure if I can really help you -- there is a lot here that's going to be very specific to your setup, needs, etc.. Besides, I like client bridging, and security (a lot), so don't have much experience with long-range WDS and unsecure performance.
There's going to be at least a slight drop in performance due to security overhead. I take this as a must-have for my needs. Perhaps in your case, if security is not important, you could take the unsecured = faster = better and just go with it.
The best way to find out about performance is to measure it yourself in your own environment. Nobody has a database of all possible hardware/versions/configurations to give universal performance stats. Esp. in wireless, things vary a lot.
You can use something like PCTTCP to measure performance point-to-point, and try various options.
Note also that wireless performance in itself is a changing beast. One day, you could have great performance, and the next day, much lower performance because someone's using a cordless phone or microwave, etc., etc., in the neighborhood.
Here's an intro to WDS, with further links:
http://en.wikipedia.org/wiki/Wireless_Distribution_System
Perhaps if you have very specific questions, I can help you. Actually, I suggest taking wireless questions to one of the Wireless forums -- presumably the people who deal with wireless all the time and with more products gather there.
Perhaps the reason I write about wireless bridging and related features is because I really like wired networking better
Especially gigabit