Abstract nouns such as "consistency", "beauty", "quality" normally don't take an article, unless we are talking about a specific instance.
So if we were reviewing a particular show or concert we might talk about "the consistency of this performance" or "the consistency of the performance"; if we are talking about an actor's prowess we might say "the consistency of his performance" (even if we are not meaning a single performance, we have still specified it to that actor).
But if we are talking in general, we would say "consistency of performance".
There is not always a clear distinction, and in some cases it is possible with or without an article.
[I've just realised, rereading your post, that it probably relates to performance at work rather than artistic performance, but my reply still works.]