Cubase10 Slow Play and Stop Playback the longer the project gets


ai currently experience a 3 second slowdown each time I press stop or move the playback cursor at another position.
My arrangement is pretty full (orchestral with Vienna Ensemble Pro) and its about 1 hour of orchestral mockup.
When I start at the beginning of the project cubase reacts fast.
The further I try to Stop and move the playback close to the end , the slower cubase gets. ( I realised this and it gets slow after about 30 minutes of music).

I also tried to delete the first 30 minutes of music and cubase handles stop & playback fast, so it definitely has something to do with the length and complexity !?!

Anyone experience the same ?

Cheers, lokotus

using cubase 10 on win 10 64bit with stable rme drivers and a lot of sufficient ram + a very good Nvidia graphic card

self note: it seems to be involved with the cubase midi settings especially to “follow notes” : the longer the project gets, the slower everything gets with this option turned on, which doesn’t make sense since cubase should only look at the current notes and not all the notes before the playback line close to the end of the piece