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copied!<p>There are two different questions here: speed when reading/writing, and arithmetic performance. Those are orthogonal. When reading or writing a large array, of course, the speed depends on the amount of bytes read as O(N), so using <code>short</code> over <code>int</code> (considering VC++) would slash the time by ~1/2.</p> <p>For arithmetic, once the operands are in registers, the size of the type doesn't matter so much. IIRC, between types in the same category, it is actually the same (so <code>short</code> isn't any faster or slower than <code>int</code>). Using 64-bit integer types on a 32-bit platform will have a penalty, naturally, since there's no single instruction to handle that. Floating-point types, on the other hand, are simply slower than all integral types, even though <code>sizeof(float)==sizeof(int)</code> on VC++. But, again, operations on <code>float</code> aren't any faster than operations on <code>double</code>; this is assuming default FPU settings, which promote all operands to 80-bit extended floats - this can be disabled to squeeze out a bit more out of using <code>float</code>s, IIRC.</p> <p>The above is VC++ and x86 specific, as requested by the question. Other platform, and especially other architecture, can differ radically.</p> <p>The best one data type that is most efficient to work with as number counter (low or not) is <code>int</code> - usually regardless of the architecture and implementation (as the Standard recommends it to be the preferred word size of the platform).</p>

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