There is no simple answer for your question.
For high quality fonts licensed from reputable font foundries, the pair kerning information in the fonts is for most designers more than adequate. For fonts with somewhat less of a pedigree, the optical kerning may but not necessarily yield better results.
Much of this has to do with taste.
Yes, there is a bit more overhead in use of optical kerning, but not something that would generally be noticeable.
In general, pair kerning issues in large point sizes (i.e., headlines) tends to be much more noticeable. But again, whether you need or want to use optical kerning in lieu of using the kerning metrics provided with the font really depends of the fonts in question and your taste.