Not 100% sure but AFAIR it was an earlier Version of Raspbian running Qwt 6.1 with Qt4 ( using X11 paint engine ). But when using X11 much of the work is done in the X Server what needs to be taken into count, when comparing systems.

I recommend simply to install Qt4 on your system and build Qwt for it ( maybe there are precompiled packages available ? ) . Then you can compare the oscilloscope example running it with raster or x11: see .http://qt-project.org/doc/qt-4.8/qap...GraphicsSystem