"So... why didn't that work the way you wanted to?"
"I didn't move fast enough."
This is a conversation I often have with my students in class. The student has correctly identified an issue in tempo (typically everything else is being done correctly) but they've made a mistake in the aspect of tempo that was in error (Capo ferro describes tempo in several ways).
The issue was not that they didn't move quickly enough. The issue was that they didn't act soon enough. In a word, then, the issue was timing.
In your practice it is important that you are able to identify issues of timing and speed correctly. It is simple to blame not acting fast enough on your challenges but, in practice at least, if you're both moving at the same speed then can the blame really be placed on not moving quickly enough? Timing is a much subtler challenge and, in my mind, much more important.
Can't tell if timing is an issue? Ask someone else! Ask your training partner, your instructor, your fellow students, that guy watching from outside.
Clint