## Faster computation of \$ke^{-(x – h)^2}\$

The question is quite simple; almost every computer language today provides the $$\exp(x)$$ function in their standard library to compute expressions like $$ke^{-(x – h)^2}.$$ However, I would like to know whether this function is the fastest way to compute the above expression. In other words, is there some way to compute $$ke^{-(x – h)^2}$$ faster than $$\exp(x)$$ in standard libraries while keeping the result very accurate?

I would like to specify that Taylor series will not work for my application, nor will any other polynomial approximations.