Thanks for the measurements. That's much faster indeed than on my laptop and even quite decent (besides the peak memory use). Compared to the C++ native version of similar apps on my Linux i386 and Windows x86 this is about factor 10/20 (Linux/Windows) more RAM in steady state and factor 25/30 (Linux/Windows) in peak. Start time of the C++ apps (not QML) is factor 6/3 (Linux/Windows) slower.

Btw. I noticed that on my machine memory use is higher on Chromium and performance even worse than with Firefox. So it seems to depend on browser type/version, and someone in this thread said that there is no support for Safari.