I have just started a new batch of beer.

Unlike my first 2, this one required 'no added sugar'. I had 2 cans of
extract and a packet of yeast.

After mixing the extract with boiling water, I then topped up to the usual 5
gallons (just under in this case) and added my yeast. Again, unlike in the
past, I previously prepped the yeast in a cup of warm water. This I then
added to my fermenting bin.

By the end of day 1, I could tell that everything was active as a large foam
had formed on the surface.

It is now the end of day 2, beginning of day 3 and this has begun to
disperse. At no point was there enough C02 to start off the bubbles in the
airlock!

Could primary really be finished this quickly? Little more than 60 hours
seems extremely quick to me (started at about 6pm Monday eve it is now
7:30am Thursday)...

Thanks