The test session you have sent has “Speedrum” which not only has over 1800 parameters but also some 20+ MB internal state (which needs to be serialized). Redux is a bit better, but still the “You can leave your hat on” session file is 85 MB, most of which is VST state (samples probably). The bottleneck there is the internal plugin state.
No. The problem is that the GUI waits until the save is done. Save does not happen in the background.
Thank you very much - that was i great info for me.
I searched a lot about performance and the result for freezing graphics is, that Ardour saves from time to time the project - and the mentioned project that takes 3 seconds on a SSD and about 5 seconds on HDD. So i can say that is “normal” and don’t need to worry about a corrupt system, bad driver or whatever.
BTW: Can the interval, when Ardour makes a backup, anywhere changed?