> Basically, a GTK app maps to the screen almost instantly. The
> delay is imperceptible - the window maps before your finger
> leaves the return key.
>
> A Qt app takes significantly longer. On my machine, the delay
> seems to be about 1/2 to 1 second.
To all the other valid comments, I'd like to add that the choice of
programming language might also have significant impact on
performance. In C++, it is possible to write programs which consume a
lot of processing power, without that effect being directly visible
from the source code. For example, creating and destroying thousands
of objects, or invoking numerous virtual functions would have such an
effect.
It was proposed that the usage of the X protocol in GTK is more
efficient than in Qt. To verify whether this is the case, run both
programs with strace, and count the sheer number of system
calls. Also, count the number of bytes passed to system calls
(especially read and write).
To find out where the time is going inside the libraries, you'd need
to compile both libraries, and the applications, with the -pg option
of gcc(1), and analyse the outcome with gprof(1); this is what was
already recommend when Andreas suggested "profiling".
Regards,
Martin
