I can't connect signal QProcess::started() to a slot

[yogeshgokul]

I hope it's not slow because it's built with QT

Not at all. Its slow on windows because its compiler and debugger(=GDB) is slow. Creator can be used with MSVC on Windows, too – even for debugging.

In your experience, applications made with QT are slow? do they have other downside?

No they are fast enough. Coz C++ is fast.