‘real-time peak’ meter constantly hitting red on Record-enabled midi tracks

When selecting MIDI tracks in Cubase the red ‘Record’ button is enabled (necessary, of course in order to play / record on that track.) This uses a lot of CPU compared to when the ‘Record’ button (or the ‘Monitor’ button next to it) is off. Synths will max out my CPU - ‘real-time peak’ meter constantly hitting red… audio output glitching etc. If I select a non MIDI track during playback (e.g. an Audio or FX track) the CPU meter drops right back. No problems. Do you know what might be causing this? (Some kind of MIDI in / out loop perhaps?) I’ve had the issue for years but synths these days seem to demand more CPU. Any suggestions would be very much appreciated.
Thanks… Alan Zipper (I use Cubase versions (9, 9.5, 10 & 10.5) on a MacBook Pro. OSX Sierra 10.12.6)

Hi and welcome on the forum,

Where is the MIDI Track routed to? Is it routed to hardware synth or to a Virtual Instrument (VSTi), please?

Hi Martin… thanks for your reply.

The track is always routed to a Virtual Instrument.

The only hardware I use is a Korg USB MIDI controller keyboard - to input MIDI - but even when it is disconnected the issue occurs.

(Sometimes I use the MacBook Keypad to input MIDI - same issue)

Cheers… Alan


Once you enable Record on the track, the track switched to the real-time mode. The track is expecting incoming data, so it cannot be pre-processed as the other tracks. Therefore the CPU load increases. The only time the processor has to process the data is the one provided by Buffer Size. For the other tracks, the processor has more time thanks to the ASIO-Guard.

Right… thanks for the explanation. Increasing the ‘Buffer Size’ helps… but of course this increases Latency.