<p>I have a Win32 console application which is doing some computations, compiled in Compaq Visual Fortran (which probably doesn't matter). </p>

<p>I need to run a lot of them simultaneously.</p>

<p>In XP, they take around 90-100% CPU together, work very fast.
In Vista, no matter how many of them I run, they take no more than 10% of CPU (together), and work very slow respectively.</p>

<p>There is quite a bit of console output going on, but now VERY much.
I can minimize all the windows, it does not help. CPU is basically doing nothing...</p>

<p>Any ideas?</p>

<p><strong>Update:</strong></p>

<p>No, these are different machines, but they run relatively the same hardware. 2. Threads are not used, this is a VERY OLD (20 yrs) plain app for DOS, compiled in win32. It is supposed to compute iterations until they meet, consume all it has. My impression - VISTA just does NOT GIVE IT MORE CPU</p>

Is it the same machine hardware on your Vista and XP? It might use just 10% of the Vista because it doesn't require more. Are you using Thread? I think it requires more information about your project to have a better idea. Have you try to use a profiler to see what's going on?