  Large samples of experimentally produced graphene are polycrystalline. For
the study of this material, it helps to have realistic computer samples that
are also polycrystalline. A common approach to produce such samples in computer
simulations is based on the method of Wooten, Winer, and Weaire, originally
introduced for the simulation of amorphous silicon. We introduce an early
rejection variation of their method, applied to graphene, which exploits the
local nature of the structural changes to achieve a significant speed-up in the
relaxation of the material, without compromising the dynamics. We test it on a
3,200 atoms sample, obtaining a speedup between one and two orders of
magnitude. We also introduce a further variation called early decision
specifically for relaxing large samples even faster and we test it on two
samples of 10,024 and 20,000 atoms, obtaining a further speed-up of an order of
magnitude. Furthermore, we provide a graphical manipulation tool to remove
unwanted artifacts in a sample, such as bond crossings.
