Floating point operations speed

Question

Is floating point multiplication with 0.0 faster than average fp multiplication? The same question about adding 0.0 and multiplying with 1.0.

For the question to make exact sense: Is it faster on recent Intel CPUs?

Answer 1

No, not on modern hardware. Modern hardware can perform all normal double precision multiplications/additions/subtractions in one or two cycles. Possible exceptions to this are denormalized numbers and special values like +/-zero, +/-infinity, and NANs. These exceptions take longer if there is a difference.

However, as with all performance related questions, truth is only in measurements. If this is important to you, measure it, then you know what to do.