The fact that the computational complexity of wavefield simulation is proportional to the size of the discretized model and acquisition geometry and not to the complexity of the simulated wavefield is a major impediment within seismic imaging. By turning simulation into a compressive sensing problem, where simulated data are recovered from a relatively small number of independent simultaneous sources, we remove this impediment by showing that compressively sampling a simulation is equivalent to compressively sampling the sources, followed by solving a reduced system. As in compressive sensing, this reduces sampling rate and hence simulation costs. We demonstrate this principle for the time-harmonic Helmholtz solver. The solution is computed by inverting the reduced system, followed by recovering the full wavefield with a program that promotes sparsity. Depending on the wavefield's sparsity, this approach can lead to significant cost reductions, particularly when combined with the implicit preconditioned Helmholtz solver, which is known to converge even for decreasing mesh sizes and increasing angular frequencies. These properties make our scheme a viable alternative to explicit time-domain finite differences.