I use qt 4.6.1 on windows and the speed of flash in qwebview compared to other browsers such as firefox, chrome, or IE is very slow. The CPU jumpes to 50-70% on my system and a similar case was here. And another case here. It's not just my application, but the demo browser also has very slow flash. I do not see why the other browsers can play flash much faster with less CPU if qtwebkit uses the same plugin as they do.