qDebug() print out text messages on the console, according to what I know print out text message is expensive.
But if I dont set CONFIG += console, will it still cost time?
Otherwise I need to comment it one by one by hand?
From Qt documentation:
This function does nothing if
QT_NO_DEBUG_OUTPUTwas defined during compilation.
So if you want to disable
qDebug() in release build, you can add next line to your
.pro file (taken from here):
CONFIG(release, debug|release):DEFINES += QT_NO_DEBUG_OUTPUT
See also this question.