Super Slow installation execution...

[Steve]

I have been struggling for years with certain Installs that take an extremely long period of time to appear on screen. The initial IA run progress bar would appear on the screen almost instantaneously, but then, depending on the PC, it could take from 2 minutes to 5 minutes for the first dialog to appear.

I just figured out that the Application Runtimes are the cause of the problem.

The way I discovered this was that I added the 'Microsoft Visual C++ Runtime 8.0 (includes ATL and MFC) Service Pack 1 (x64)' and suddenly my very quick install changed to an install that would take close to a 1.5 minutes to show the first IA dialog. When I removed the runtime, the problem disappeared along with it.
I haven't yet looked into what is going on within IA's runtime 'check' that is causing this to happen, but suffice it to say that the more MS runtimes I added, the exponentially longer it took for the installation to begin.

So if you are experiencing extremely long installer initialization times, drop your MS Visual C runtimes and see if that improves that situation.

[JohnGaver]

Some runtime installers perform thorough system scans which could take a while based on system load, affecting especially obsolete hardware with mechanical (spinning) drivers.

You would be best advised to display a "preparing installation" dialog at the start of your setup, which is typically available with other installation platforms, but is mostly unnecessary with InstallAware (congratulations on having come up with a scenario which would require it).

You may use the standard "wizard" dialog which ships with all setup themes to create your new "preparing installation" dialog in conformance with your existing setup theme, so it all looks very nice and in conformance with your design.