Reduced performances in Qt 4.8.0 after RC

Testing my application on Windows 7 with Qt 4.8.0 final precompiled binaries (from Qt SDK) and with 4.8.0 Release Candidate precombiled ones (from Qt SDK) shows that the final version has a reduced smoothness compared to the RC libraries.

Morehover, updating the DLL files one by one, I discovered that the updated library that reduces the smoothness of the app is QtCode4.dll.

I observed this behaviour on every Windows 7 PC I could test it. You can try it yourself by downloading this zip containing my application http://code.google.com/p/dukto/downloads/detail?name=DuktoR5-Portable.zip and source code is here http://code.google.com/p/dukto/source/browse/ (in trunk). The ZIP contains the Qt 4.8.0 RC DLLs provided some time ago by the Qt SDK. You can try replacing with the 4.8.0 final DLLs to see what happens.

Directly compiling the executable across the final version doesn't solve the problema.