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Performance degradation from Qt 5.5.1 to Qt 5.6.0 and newer



  • Hi, did anyone of you experience performance loss in multithreaded Qt applications when moving from Qt 5.5.1 to .5.6.0 (or any more recent version of Qt) compiled with minGW and running on Windows (we tested with Windows Server 2012 and 2016)?

    Our application processes up to 150000 UDP packets per second. With Qt 5.5.1 we see drops of at most 15 packets per second. With Qt 5.6.0 we see up to 80 packets dropped per second. We used the very same compiler and the tests were run on the very same machine with the very same input data.

    Did anyone here experience something similar while upgrading from Qt 5.5.1? If so, did you find the cause? Any hint regarding similar scenarios might help us.


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