[gjm11]

So he found that dynamic dispatch was a lot more expensive. Fair enough and not very surprising. But let's quantify it a bit in absolute terms. The dynamic version of the code took 1.25s to run, during which time it performed approximately 8 x 10^8 virtual function calls. That translates to a cost per call of 1.5 nanoseconds.

From which my takeaway would be: In inner-loopy code for which an extra nanosecond or so per call is critical, you should avoid virtual function calls. For anything else, don't worry about it.

[MichaelGG]

1.5 nanoseconds per call in the best case. In some huge monstrosity where you've got to go chase down object headers not in the cache, things may be quite different.