Long delays when working in the Qt3DS editor

We have a large presentation in our project that we cannot divide into sub-presentations because of the bad effect on performance. And we see delays of 15-20 seconds in the editor for any interaction with the presentation.
Given the issues with merge conflicts, this issue significantly reduces development speed. Even to copy the result of the work done from another presentation takes a lot of time.

Please watch the video and I also shared the project on our FTP: FTP\qt\ftp_data\From_Harman\Qt3DS-4151