LAG and AUDIO OUTBURST when moving around MIDI files

If I’m moving around my template, when I change from one track to another data is sent to all my MIDI tracks, which makes my computer freeze during a few miliseconds (noticeable, but not much). This could break my audio (at least in 9.5).

I have a fairly big template (almost 500 tracks, mainly due to the akward/oldstyle MIDI-Return need) with an Instrument Rack setup.

It happened in Cubase 9.5 and it happens also in Cubase 10.

Sometimes, this overloads the bus and I get the audio broken or the group track, while it’s sounding a full blast square-like sound all the time (which renders cubase unusable). I can solve this noise creating a new group track and redirecting all the stems to it but it may happen again.

It didn’t happen until recently but it is a very bad thing. I don’t know if it’s a cubase thing or if it’s something related with my template.