Consider the following simple example:
The speed of green bar is incosistent when switching between different versions of Qt on Windows 7 (x64). The speed is equal and as expected for versions 5.1.1, 5.2.1, and 5.3. Alas, on 5.4 animation is running approximately 2 times faster than desired.
No such behaviour for Mac OS X 10.10, and Ubuntu 12.02 (verified for the same list of Qt versions).