How quickly do larvae spawn in Starcraft 2?

By default it is 15 seconds on hatchery,lair and hive(it stays same).

Depending on gameplay speed:

• slower = 24.9s
• slow = 18.8s
• normal = 15.0s
• fast = 12.5s
• faster = 10.9s

Note: The queen's "spawn larva" has a 40s cooldown and spawns additional 4 larvae,but the building wont start producing more larvae until the number of them falls under 3 for that building.

Max number of larvae available for one building is 19.

I timed it myself from a beginning game I stared a stopwatch at the same moment i qued morphing a drone and stopped the watch as soon as i saw a Larva pop up. The time i got was 13 seconds i did it a few times and was off by roughly .1 to .2 seconds each time because of my reaction time of course.

If you're talking about Spawn Larva Queen ability:

• Spawn Larva takes 40 in-game seconds.
• According do game-to-normal-time relations on "faster" it 72.5%

So: 40 s * 0.725 = 29 s