Well I think there are 2 sides to this issue.
1. If the pace is fast, it just means that a team will shoot early on in the shot clock. Hence it doesn't tire players faster.
However
2. If a team shoots early on in the shot clock, the opponent will have more possessions too and hence the players have to run up and down the court more frequently, thus tiring the players faster.
Since I joined BB, people kept saying that faster pace means players will tire out quickly, so I guess I've been brainwashed to think that way :P. I'm also interested to know if using fast pace offense actually make the players tire faster.