QtWeb.exe (portable version, location C:\Programme\QtWebBrowser) runs permanently 40-50% load on the
Intel Core 2 Duo CPU T5750 @ 2.00GHz even while not browsing the internet. How can I fix this problem ?

Found out this happens only if the "Bookmarks -> Popular Links -> Google - Found out this happens only if the "Bookmarks -> Popular Links -> Google - search engine and more" link is open in a tab...

Very strange, but I also noticed this trend on an Athlon XP 2000+.  CPU usage hovers around 70% when one window with 7-8 tabs open.  Not necessarily when the Google search engine is running…just all the time.

This strangely stops, however, when I open a new window.  For instance, this reply is in a new window with just one tab - there is another window with 8 tabs open:  CPU usage is 15%.  When I post this message, close this window and go back to the other window, I am sure that CPU usage will go back up to 90%.

[edit1] Sure enough, when I clicked on Post, the CPU usage went to 80%.
[edit2] When I close the additional window and go back to my main window (with the 8 tabs open), CPU usage goes to 80%.  But as I am typing this message in the main window (with 8 tabs open), the CPU usage drops to 15%.  When I Post, it will go back up to 80% and stay there.

Very very strange.

I've noticed this once or twice, also noticed that the mem usage is absurdly high (over 127 mb) for some bizare reason at times.

Problem was in Qt timers implementation ( javascript::SetTimeout() ), so appeared on JavaScripted pages which used timers, like google and youtube.

Try  QtWeb 2.0 build 041, problem found in Qt+WebKit implementation of SharedTimer (SharedTimerQt.cpp).

Portable Qt implementation of Timers replaced with native Windows timers, which provided huge performance gain...

Fixed now.