I actually measured it. VEPpro7 takes exactly the same amount of time to load the projects I tried compared to VEPro6. Exactly the same. test projects were around 100 tracks of VSL instruments. Its always possible other plugins have issues, but measure it before saying it takes 50% longer, I doubt it.
Now that being said, could be because of 100 instances too, I don't use that setup, Measure it exactly and report it to VSL if so. I have found them to be pretty responsive when real bugs are actually found. way more responsive then a lot of other software companies. I give them that..
I can also tell you with measured certainty also that VEPro7 is significantly better CPU performance then VEPro6, but only if you're on Mojave. If you're on an older version of OSX, then VePro6 is in fact a little more performant then VePro7. VePro7 is making use of newer GUI related libraries that are apparently making better use of Mojave, Metal and all that... its definitely better performance, particularly with regards to when the GUI is open, and when using HiDPI, etc. I did measured and methodical performance tests and also had some communication with VSL engineers who also saw much superior performance on their Mojave based system as well.