07.09.2021 
In 2019, I optimized QStringList::removeDuplicates() by using std::pmp::unordered_set with a std::pmr::monotonic_buffer_resource, when available. The class that I wrote to encapsulate this optimization has since been re-implemented three times. The latest iteration has recently landed in KDToolBox. If you have code that looks a bit like this: then you should read on.