If Q_WS_X11 and QPA_XCB are undefined it's possible to use Qt's pixmap cache to speed up the drawing.
ATM, this seems to be broken (for HiDPI and Qt5 only?). The placement of the text isn't correct while pixmap cache is enabled. Does it make sense to have this feature anymore on recent systems? I'll attach two screen shots to illustrate the problem. Stephan
