  The large-$N$ limit of $O(N)$-symmetric bosonic field theories, or
$U(N)$-symmetric fermionic field theories, is amenable to a saddle point
approximation. As a result, there is a family of closely related algorithms for
efficient lattice simulations in this limit, even in the presence of fermionic
or real-time sign problems. These can be used to study quenches, or other
observables for which
