I found a few more things;
- internet connection doesn’t affected when the editor works in background, the editor worked in the background for 30min and internet hasn’t interrupted. (no never ending page loads or yellow exclamation mark on the connection icon at right bottom)
- internet beginning to interrupt when I actually do something with the editor i.e. working on and compiling materials, baking lightmaps and fiddling in the staticmesh browser.
- also it seems like the engine using only one core in editor (%25percent usage in taskmanager) and it can go up %30percent when baking lightmaps. still pretty low, I have amd phenomII am3 socket quad core.
I’m not even sure where to start looking, some hints appreciated.