When you say drain too much time, you mean due to it being a distraction? Then I would try to optimise it so that it's playing the slow-mo immediately, and maybe at 50% speed so that the 3 second buffer is played out in just 6 seconds.

If you wanted to be REALLY clever, you could get it to start playing the slow mo the moment the ball is detected.

Or perhaps replays could be gated behind a button push. Ball detection copies the current video buffer into an secondary buffer; the button plays whatever is in the secondary buffer.

Or you could make it a web app, and stream replays to people's phones when they're on the alley's wi-fi. That has the benefit of making an epic moment saveable and shareable.