- qtWebKit is an imported library both use, and have setup involved in the application including some online configuration of the environment.
- Since it is a shared library and not a dedicated subprocess, you could be trying to run the renderer from your main application thread, which would propagate exactly the problem I pointed out. If other aspects of that execution stack are slow, the rendering would also be slow.
- You can set allocator limits throughout the application to control the behavior of the renderer.
- You can override standard library functionality or any external behavior the renderer uses that could slow it down or speed it up.
- You can override parts of the renderer in your own code, since in qt using webkit is just a module you import.
- The caching behavior of webkit is entirely controlled by the host process. This is probably the most major cause of slowdowns when two applicaitons share the same webkit.
There are a lot of ways to influence the execution speed of a component an application is importing. In an even more generic sense, you could just reduce the scheduler priority of your render threads and it will just get less cpu time inherently, but you can do that out of the program too.