In Rack 3, modules can set power-of-2 minimum and maximum block sizes. Modules ported from Rack 2 will have min = max = 1 until the developer changes it. For example, an FFT convolution reverb might set min = 16, max = 1024. Virtual circuit modules like VCV VCF could set min = 1, max = 1024 and process samples in a fast loop.
Newly created cables will have 0-sample latency, unless adding one creates a feedback loop. In this case, the cable will use the greatest minimum block size in the module feedback group. This latency is shown on the port tooltip.
Rack 3’s engine scheduler organizes the patch’s graph topology into an ordered queue with dependencies, so the entire audio input buffer can be processed one module at a time in signal chain order, in parallel by multiple threads if possible. Feedback groups are processed as an atomic “task” by a thread, where the feedback latency is minimized based on the allowed block sizes of the modules.