On the basis of a fully discrete trigonometric Galerkin method and two grid iterations we propose solvers for integral and pseudodifferential equations on closed curves which solve the problem with an optimal convergence order uN − u λ ≤ cλ,µNλ−µ u µ, λ ≤ µ (Sobolev norms of periodic functions) in O(N log N) arithmetical operations.