In PluginProcessor.cpp, the values in m_midi_control_param_map are never erased, and since it's a multimap every time the synth MIDI learns, it adds another instance of the parameter to the map, so you can have the same parameter being controlled multiple times by the same MIDI controller, which slows down the synth when too many are added.
In PluginProcessor.cpp, the values in m_midi_control_param_map are never erased, and since it's a multimap every time the synth MIDI learns, it adds another instance of the parameter to the map, so you can have the same parameter being controlled multiple times by the same MIDI controller, which slows down the synth when too many are added.