Version Upgrade from Qt 5.2.1 to Qt 5.5.1 caused heavy performance drop

[turtle]

Hello everyone,

this is a thread I never expected to open, but today I ran into a problem when updating my Qt-version.

I was happily using Qt 5.2.1 32 bit with MinGW 4.8 and QtCreator 3.0.1 (based on Qt 5.2.1 (MSVC 2010, 32 bit)). Then I needed the Websocket support that was only added in Qt 5.3. So why not download the newest version? So I installed Qt 5.5.1 32 bit with MinGW 4.9 and Qt Creator 3.5.1 (opensource) (based on Qt 5.5.1 (MSVC 2013, 32 bit)).

At first, I could not compile my application. Then I figured out it was due to a lib of myself that I was using that was created with Qt 5.2.1. So I compiled it with Qt 5.5.1, and then I could also compile my application. But what a change! The performance has hugely dropped! I have a lot of qDebug() in my code. With Qt 5.2.1 I could see if running very fast through the console. But now, a) the color of the text is pink (any reason why? i was not debugging...) and b) the qDebug() output now runs quite slowly through the console. And opening a complex widget (no code changes!) takes 15 seconds, with Qt 5.2.1 it opened instantly!

I can only think that a reason could be that the install path is not "optimal"?

Qt 5.2.1 is installed here:
C:/Qt/...
Qt 5.5.1 is installed here:
C:/Qt5.5.1/

My computer is runnning Windows 8 64 bit.

I tried to disable the qDebug() messages to see if there is the root cause, with

CONFIG(release,release|debug){
    DEFINES += QT_NO_DEBUG_OUTPUT
}

CONFIG(release,release|debug){
    DEFINES += QT_NO_DEBUG_OUTPUT
}

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But this did nothing at all (I mean: the qDebug()-messages did not disappear), even after cleaning and rebuilding everything.

Or can the problem be due to the QtCreator community edition?