[Interest] Application build times using Qt4 vs Qt5

[Thiago Macieira]

On Tuesday 29 July 2014 11:22:52 Adam Light wrote:
> I've noticed that compiling my application takes considerably longer when
> compiling using Qt5 vs. Qt 4. This is true on Macintosh 10.9 and Windows 7.
> I'm comparing builds done using the same machine with the same application
> source code.
> 
> For example,
> Macintosh:
> Qt 4.8.6: Elapsed time: 06:20
> Qt 5.4-dev: Elapsed time: 08:51.
> 
> Windows:
> Qt 4.8.6: Elapsed time: 04:51.
> Qt 5.4-dev: Elapsed time: 10:23.

The increase in build time is not unexpected. Qt 5 is bigger and has more 
complex constructs. We also forcibly include more of the Standard Library 
headers, which causes an increase in build time too.

The Windows time increase is more than I'd expect, though. As Kai said, it's 
probably caused by qmake being slow for some reason.

> Qt4: echo yes | MAKEFLAGS=-j16
> QMAKESPEC=/qtbuild/qt/mkspecs/unsupported/macx-clang ../../qt/configure
> -debug-and-release -opensource -no-qt3support -nomake examples -nomake
> demos -nomake tests -silent -no-sql-mysql -no-webkit -cocoa -arch x86_64
> -arch x86 -no-phonon -no-phonon-backend -prefix /qtbuild/install/macosx

Hint: use -confirm-license instead of that "echo yes"
-- 
Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel Open Source Technology Center