This is required. From the "RestartFlags" documentation:
> kLatencyChanged:
> Latency has changed The plug informs the host that its latency
> has changed, getLatencySamples should return the new latency after
> setActive (true) was called The host has to deactivate and reactivate
> the plug-in, then afterwards the host could ask for the current
> latency (getLatencySamples) see IAudioProcessor::getLatencySamples