Hello Gilles,
Same issue with my project.
With build 636, 59 seconds, with build 734 3 minutes and 59 seconds.
Once loaded, everything seems to work as usual...
I sent a ticket (case 505166) to VSL Support this morning about that.
Glad to see that I am not alone...
Unfortunately for me, I have to keep the build 734 because I have purchased the "Duality Strings" which needs the build 734 to be loaded correctly.
Eric