Please download and run TestApplication
Perhaps because of the warning "qt3ds.warning: Failed to load image: SubRectangle" boot time is increasing. The warning cannot be fixed in a simple way.
If we replace the texture with a png image, then a significant increase in the boot time is not observed. Also, if we replace the custom shader with the default material and use subpresentation, then there is no significant increase in boot time. Therefore, the reason may be the warning.
If a sample application is not enough for analysis, please download the project from the ftp server (From_Harman\
In the DS/EarlyHmi/DriveSpeedControl folder you can find DRIVE_3212_Group_ADAS_VIEW.uip. There is element (Scene.Layer.GroupRoad.Road) that uses subresentation in custom shader.
The difference with and without warning is ~8 seconds.