How critical is validation when it comes to program performance?
Validation should always be considered in a software program.
The amount of validation depends on what the program is doing, and
how it is doing it. If the validation is a small percentage of the
overall program then it doesn't matter much how efficient it is in
terms of performance.
There are good and bad ways (actually inefficient ways) to do
validation. If you instrument a program and find that a significant
portion of the time is spent in validation you may want to visit
the algorithms used in the validation to see if there is a more
effective way to do this.
In some cases the performance of validation of data is very
important; in other cases it is a side-effect.