Thanks to Pascal Debuisson in the LinkedIn Qt discussion group who pointed out a fix to the Qt 4.8.x rendering performance issue on Mac OS 10.9 (Mavericks). This means that I don’t have to wait for fixes on the current Qt version. One thing missing in the older version is baked on JSON parsing support, so I’ll have to find a solution to that – either go the XML way, use the QtScript engine, or use the Boost lib as I did previously. None the less, this is a minor issue.