  We introduce an efficient Langevin method to study bilinear Fermionic
Hamiltonians interacting with classical fields. Our method is suitable for very
large systems and offers high accuracy. To demonstrate the method, we study
complex non-coplanar chiral spin textures on the triangular Kondo lattice
model. We also explore non-equilibrium mesoscale physics such as chiral domain
coarsening and Z2 vortex annihilation.
