"It depends". If you have enough time to get ready, you can outdo most automatic drivers who just lift off the brake and stomp on the gas.

The fastest way to launch a manual is usually what's called a "preloaded" launch. If you watch old Top Gear you'll see Tiff do these all the time. The idea is that you tension up the driveline and get the clutch to where it's almost at the bite point and you can engage it rapidly without bounce. What you have to do is:

Stage 1 (preparation):

Set the handbrake.

Clutch down, into first gear.

Get revs up to your launch RPM (try 2.5k-3k) and hold them there.

Stage 2 (prelaunch, less than 5s before launch):

Bring the clutch up almost to the bite, to where you just start to feel it engaging and the driveline tensioning up. Don't sit there burning the clutch but get it to where it just barely starts to engage.

Stage 3 (launch):

Clutch up, accelerator down, handbrake down, simultaneously. You'll set off like you're coming out of a slingshot.