On Systemsettings i can setup on OpenGL

"Shared Memory"

and

"Texture from Pixmap"

what does these do?

They toggle KWin's usage of those OpenGL extensions, and primarily affects performance.

Yes as i thought but i still dont know which setting stands for what?

Which of those settings increase speed and which not (i think this should be explained somewhere. The handbook doesn´t tell a word about)

Unfortunately their effects upon performance are dependent on your X drivers, their versions and the card itself as well as other components in the software stack such as the kernel, mesa and X.

Is there any thumb rool? What for example can i do with my Intel Mobile 4 Series using xf86-video-intel driver

As far as I am aware there isn't, KWin activates those settings that it knows are safe if it can, only experimentation will tell you if you can activate them or not otherwise however.