Requirement for a "Best Practices Guide"

There are frequently many different ways to achieve a given goal. Often its not clear to a programmer what's the most efficient way to do something. Something that may be obvious to a programmer may infact be computationally heavy. This doesn't matter much for desktop with the greater hardware resources, but for memory and processor constrained embedded devices it can be a make or break in the success of a project.

A comment from a "Lessons learnt" from Nokia is
"The documentation does not always declare what operations can be time-consuming or "heavy""

I've also heard comments that customers are using Qt the "wrong way".

As Qt is usage is driven into Nokia and other companies, more and more it will be encountered by less skilled engineers who won't dive into the code to learn the abstractions and layer that would give them the understanding of the cost impact of each feature. As such it is important to start to build a Best Practices guide to help these developers. This is an ongoing project that requires revisiting after each release to ensure that information is has not been made obsolete. The best starting point would anecdotal information from developers and support engineers.