Many thanks to have upgraded the Boinc version on the WCG download page. Now the 6.10.58 version is the standard and indeed it is at least under Windows very satisfying. I use the CPU% parameter at 50% with three of the devices that are used by my family members and it is much better than just suspending the tasks when someone touched the mouse or keyboard.
They have quad and six core CPU's. When they need more power then just browsing the internet, like using multiple application at the same time then they get the power needed. It is now two weeks I tested it and they did not feel at all that they were slowed down by the running the WCG tasks. The major test was with my kid gaming or looking at videos and not feeling any slowdown. I could check that cores were shared effectively. The more cores the better. This new function allows a much better share of the processing power.
This also means that many users do not need any more to just have the WCG application run only as a screen saver, but could run in parallel during their normal use and not feel it. The future path is multiple cores with dual cores being the minimum standard and quads becoming more and more popular.
This function well set up, should result in a higher average crunching power for the whole WCG grid.