Foreach loops on static arrays error message

[Anonymouse via Digitalmars-d]

On Thursday, 6 July 2017 at 08:49:33 UTC, Stefan Koch wrote:
> I'd say this is not often encoutered.
> One should avoid using a different type then size_t for the 
> index, as it can have negative performance implications.

I thought size_t was what it lowered down to using if you used 
something else. What should I use instead?