Quote Originally Posted by RealNC View Post
Qt 5 is using the raster engine, so no GUI operation is actually hardware accelerated (that model of accelerating "lines" and "triangles" on 2D GUIs has been outdated for years now on most modern operating systems.) So using XCB is fine.
Qt 4 is 6.5 times slower with raster engine than with native engine on Intel G33 graphics card

qtperf4 -graphicssystem native
QLineEdit - 0.022 s
QComboBox - 0.19 s
QComboBoxEntry - 0.183 s
QSpinBox - 0.015 s
QProgressBar - 0.021 s
QPushButton - 0.016 s
QCheckbox - 0.007 s
QRadioButton - 0.019 s
QTextEdit add text - 0.057 s
QTextEdit scroll - 0.048 s
QPainter lines - 12.95 s
QPainter circles - 13.1 s
QPainter text - 1.356 s
QPainter pixmap - 0.088 s
Total: 28.072001 s

qtperf4 -graphicssystem raster
QLineEdit - 0.043 s
QComboBox - 0.336 s
QComboBoxEntry - 0.327 s
QSpinBox - 0.024 s
QProgressBar - 0.04 s
QPushButton - 0.017 s
QCheckbox - 0.014 s
QRadioButton - 0.035 s
QTextEdit add text - 0.175 s
QTextEdit scroll - 0.148 s
QPainter lines - 86.218 s
QPainter circles - 86.222 s
QPainter text - 8.689 s
QPainter pixmap - 0.867 s
Total: 183.154999 s