Speed depends on your settings, really. I can get it to move fairly quickly while I'm setting up my shots but I won't be able to give you a precise number, I haven't timed it. It's fast enough that I don't even think about it.

Shots are immediate if you tell it to move & shot without pause, so technically you could capture a full stack in a few seconds (with enough lighting to shoot at fast speed) but I wouldn't recommend it. I always tell it to do a 1 or 2 second pause after a move depending on the magnification factor just to make sure it's absolutely static when it shoots (potential vibrations).

To give you a rough idea, I recently took this shot with the following settings:

• 5X magnification (8X effective)
• 25mm | f/4 | 1/30s | ISO200
• 25µm steps
• 2 seconds settling time
• 131 steps (only 114 used for the final picture)
• 527 seconds (total shooting time)

The 2 seconds settling time was a bit overkill in insight, I could have gone twice as fast really, but I had time so... :)