TR 96-011 by Minesh B. Amin and Bapiraju Vinnakota Sequential circuit fault simulators utilize the multiple bits in a computer data word to accelerate simulation. Parallel pattern simulators simulate multiple vectors with one fault. Parallel fault simulators simulate multiple faults with one vector. Neither class of simulators is uniformly superior for all circuits. Prior to simulation, a user cannot know which class of simulators will execute more quickly for a target circuit.
Multiprocessor simulation is a second technique to reduce simulation times.
In practice, the gains from parallelism are limited for many reasons.