[Cmake] Autological Makefiles (+ VTK new build is *slow*)

[Brad King]

> Let's face it, whether there are .ncp and opt files or not, whether there 
> are fresh or not, msdev won't care :) if it's run on the command line, it 
> always take around 70 seconds (compared to 18 s. in the old tree using 
> nmake files). For a single source file.
>
> Let's try with 4 modified .cxx files (I'm rarely working on more than 4 
> classes at the same time) :
>          4 files in the new tree : 75 s.
>          same 4 files in the old tree : 29 s.
> 
> => msdev compiles faster, probably because it sends a dozen source files at 
> the same time to CL.exe (compared to nmake), but the overhead is *really* 
> big, i.e. it will *always* spend around 60 s. before really compiling the 
> files. 1 minute for each compilation.
> 
> If I run the GUI without the cache files (.ncb, .opt) :
>          the first build : 1 source file : 120 s. !! (almost two times 
> slower than on the command line, but the .ncp and opt are created)
>          the 2nd build : 1 source file : 18 s. (i.e. once it has computed 
> the dependencies, it seems to spend only time on compilation/linking)
Have you tried running the command line msdev when there are no .ncp or
.opt files?  Does it create them?  That may help indicate whether it uses
them at all.

There is another possible explanation, though.  How long does the GUI take
to load when you run it for the first time and load the project files?  I
would guess that most of the work done once when you first load the GUI is
done each time the command line tool runs, and that the time difference
has nothing to do with dependency building.

Unfortunately, neither explanation gives a solution to the problem.

-Brad