When too much MIDI data is present in a single MIDI cable or between a MIDI Interface and the host computer timing anomalies can occur. This phenomenon, often called “MIDI log jam”, is the result of the MIDI processor having too many time sensitive events to manage into a serialized communication. Eventually the data gets dense enough that some bytes must wait in a buffer to be sent. If the wait is long enough you can notice timing problems. It is usually a good idea to “thin out” your MIDI data some by removing any extraneous continuous controller data, or any other types of information that can generate lots of data if you notice these problems.