Performance of Web Audio graph is heavily dependent on skipping processing of silence because processing in unreferenced nodes continues until they are garbage collected. Nodes should produce a null chunk when they know the output is silent. If not, the rest of the graph downstream will need to process the chunk. For WaveShaperNode, that can be when the center value of the curve array is zero and the input is null, though resampler latency should be considered.

There is already a test on aInput.mChannelData.Length(), which causes bug 961932.