The speed an instrument CAN be played at depends in many cases on the distances fingers etc need to move to produce the series of notes. Valves on a trumpet move a shorter distance than those on a tuba, so the trumpet has a speed advantage built in. That doesn't mean that some tuba players cannot play faster than some trumpeteers, but that is despite the instrument, not because of it. Same goes for larger and smaller instruments within a family of instruments.
Comparing things such as fiddle and tin whistle is a more difficult proposition. Often a tune is written for or created on a specific instrument. The intervals, fingering and jumps between particular groups of notes are specifically suited to that instrument, often to make fingering simpler.Some tunes are simple on one instrument but incredibly difficult to play on some other instrument.

Some players are incredibly fast, but if you actually listen to what they play, they produce the speed by either missing out half the notes or play something which isn't actually the tune.

As fot the speed of a fiddle...
A banjo has a longer neck an heavier body, so you can build up more momentum with the swing. It therefore goes faster when you let go.
A bodhran flies further, but not necessarily as quick.
As for melodeons, what matters is accuracy of the throw rather than the speed.
Quack!
GtD.