My main project is about the same launch time. However customer modification projects launch much quicker. I feel the threshold is under 2000 pictures in the album.
Use a TEMP project for your current target of displays that you are working on. That will launch much quicker. Use a control file to get the engine to load the main project.
Panel changes are the only thing you can modify for the Development launch... so screen mapping changes require a new launch but... for scripting add a temporary button and put the code into its script property ( NOT OIS LINK ). Then you will be able to adjust the script and continue testing it in that same launch.
Later you can import the TEMP project contents into your main project.
Example control file contents with commented commandline for the launch...
; /cc /GUpd=1 /GUpdS="" "C:\Workspace\v63\TEMP.lwc"
[RELOAD]
UPDATE=MAIN.lwr, C:\Workspace\v63\MAIN\bin\MAIN.lwr
[S2K]
RUNTIME=TEMP.lwr
RUNTIME=MAIN.lwr