I’m working part time on improving the performance of QtWebKit (memory usage and raw speed) and I have created some tools to create an offline copy of a number of webpages (gmail, yaho mail, google, news sites…).

Using these sites I have created special purpose benchmark reductions. E.g. only do the image operations we do while loading, while loading an painting, load all network resources. One thing I have noticed is that with a couple of small things one can achieve a stable and noticable speedup. These include not calling QImage::scanLine from within a loop, avoid using QByteArray::toLower or not use QByteArray::append(char) from a loop without a QByteArray::reserve.

I have created a small guide to Qt Performance, I will keep it updated and would like to hear more small hints that can be used to improve things. If it makes sense I can migrate it to the techbase as well.