I wouldn't particularly say that this method is conductive to speed. However it could allow you to take many shortcuts over sandbars and large shallow areas encountered in distance races. Here's a little story about my best (though inadvertant) display of sailing without rudder-guidance:

I went to the Sarasota Sailing Squadron's Labor Day regatta a few years ago. The wind was blowing onshore at a gentle 7 knots. When I got there, there was only one spot left on the shore large enough to fit a catamaran, though four more cats were being rigged in the parking lot. Not wanting to take the last space, I put my boat in the water with a great shove and then tossed my anchor out as far as possible, which got me about 50' away from the shore after letting enough scope out to hold (it's about 3' of water).
I pulled the main up first and sheeted it tight to tension the rig. Then I raised the Jib and uphauled it nice and tight. This way when I sheet the main in, the jib's luff is tightened, and when I let the main out, the jibs luff is loosened.
When I had just cleated off the jib halyard the anchor line came undone and the boat began drifting back towards the shore lined with boats. I ran back to the rudders to put them down, only to find they were still tied in the up position for trailering! I stood in the center of the rear trampoline with the jibsheet in one hand and the mainsheet/traveler in the other. I let the main all the way out and held the jib backwinded to turn the bow off the wind (standard 'out-of-irons' proceedure). When the boat had turned 90 degrees to the wind (and was about 20' from shore and in 1' of water), I let go the jib and sheeted it in on the leeward side to drive the boat forwards. There were some little kids (none could have been more than 10 years old) playing in the water which I had to pass before I could round up and tack. I zipped past them while they all waved and hooted at my trick of sailing in knee-deep (on them!) water on an 18' boat! After I'd past them I sheeted the jib in tight, traveled the main in half-way and sheeted in some. When I had a bit of speed up I sheeted the main tight and pulled the sail over-center to tack. As soon as the jib back-winded I let the main out all the way on the 'new' leeward side of the boat and let the jib push the bow back down until I was now heading back towards my floating anchor-line. I let the jib go and loosely sheeted it from leeward. I left the main traveled out but sheeted in enough to balance the jib. When I came up to my anchor-line I tacked right on it, then walked to the bow while the boat drifted back and grabbed the line out of the water.
I made sure the next knot held!