Darren i have some theories.
Basically I agree, there are major issues or flaws in how Cubendo handles the saves.
Generally the main issues with save times seems to be large amounts of any or several of the following:
Automation
Process history data
Amount of files in the project
Vari audio data
In my case it’s mostly process history data and automation data that causes slow saves.
You can test this by for example:
Freezing all edits ( don’t do it on the original project as it is not undo able reliably).
Delete all automation in project.
Flatten all vari audio events.
Reduce the number of files in the pool.
None of these are really solutions, just possible routes to show where you’re personal save time issues lie.
Some possible help on the way:
If it is caused by automation you can reduce the amount of automation in various ways.
You may be able to freeze some edits or flatten some or most vari audio data.
You may be able to split the project in multiple parts to keep the number of files lower.
Any or all oft he above without to severely affecting your workflow.
But yes the issue is bad and has to be resolved by Steinberg for real.
Especially as for most users it will be a combination of all these things causing the slow save times.