> Micro optimization is rarely of great importance as the effects of > large scale algorithm > issues dominate in virtually all situations. If you had one of the > situations where > instruction timing was an issue you probaly would not have asked the > question. Is the old > story of the price of yachts. If you have to ask then you probably can > not afford one!
This isn't a micro optimization issue. The reason why it's necessary to understand the relative efficiency of certain data types is to be able to make adequade decisions regarding how certain algorithms are implemented.
Instruction latency, in this context, is only important to get an estimate of the cost of using specific numerical data types, because if you know beforehand that implementing an algorithm as algorithm<double>() is significantly more or less efficient than implementing it instead as algorithm<long int>(), you will be able to choose the best way to implement it.
So, it isn't a micro optimization issue. It's instead a best practices issue.