Flash worms follow a precomputed spread tree using prior knowledge of all systems vulnerable to the worm's exploit. In previous work we suggested that a flash worm could saturate one million vulnerable hosts on the Internet in under 30 seconds [18]. We grossly over-estimated. In this paper, we revisit the problem in the context of single packet UDP worms (inspired by Slammer and Witty). Simulating a flash version of Slammer, calibrated by current Internet latency measurements and observed worm packet delivery rates, we show that a worm could saturate 95% of one million vulnerable hosts on the Internet in 510 milliseconds. A similar worm using a TCP based