We're creating a Qt app which is basically a QtWebKit window for viewing a web application. The web application's frontend is written in ExtJS and it is running very slowly in some parts (e.g. some screens with multiple grids or complex layouts). My question is: is there a way of configuring the Qt app to make increase the performance of its JavaScript/rendering engine?
Thanks!
There is no way to tune webkit, so you can't tune it from Qt, either. But that doesn't mean you can't do anything. Here is a checklist of things you can try:
Make sure the performance is actually lost in the place where you think by measuring it with a profiler. I'm wrong 90% of the time when guessing what causes bad performance problems. Have a look at how many reputation I have and then think hard whether you are really sure you can do better :-)
If a profiler isn't an option, add timing information to the code.
Is it also slow in a normal web browser? If so, try to improve the JavaScript code. There are tools to run/profile that as well. Some are even built into your web browser.
Consider implementing part of the UI without ExtJS (and the overhead it brings along). Do you really need a full-fleshed out grid to display static data that can't be sorted? Maybe a plain HTML table will do.
Try a newer version of Qt. 5 just came out and it contains a more recent version of webkit.