А я поняла латентность, как задержку перед выполнением следующей команды, и вроде бы AlexD был того же мнения. http://www.agner.org/optimize/instruction_tables.pdf
А в источнике, где я цифры брала (см. ссылку), ей дается вот такое определение:
Latency
The latency of an instruction is the delay that the instruction generates in a dependency
chain. The measurement unit is clock cycles. Where the clock frequency is varied
dynamically, the figures refer to the core clock frequency. The numbers listed are
minimum values. Cache misses, misalignment, and exceptions may increase the
clock counts considerably. Floating point operands are presumed to be normal numbers.
Denormal numbers, NAN's and infinity may increase the latencies by possibly
more than 100 clock cycles on many processors, except in move, shuffle and Boolean
instructions. Floating point overflow, underflow, denormal or NAN results may give a
similar delay. A missing value in the table means that the value has not been measured
or that it cannot be measured in a meaningful way.