Koen Verbeeck (3/28/2013)
At least, if the destination table isn't too large.
If there can be duplicate IDs in the source data file, it means the lookup has to be used in non-cached mode, which is also a performance killer. But in cached mode it should run quite fast, subject to the above condition.
If you haven't even tried to resolve your issue, please don't expect the hard-working volunteers here to waste their time providing links to answers which you could easily have found yourself.