I am having the same issue. I am using the Synchron Harp, Strings Pro and Oboe d'Amour on a pretty large project. ALL of my other AUs are playing fine and without any issues except for the Synchron Strings Pro. It is bogging down the system badly and it's so frustrating. Since switching over to iLok this has been the one constant CPU issue with VSL and it's really frustrating. Any news or updates would be great. I have tried all the things people here have mentioned and still no resolution.
Thanks,
Seth
MacPro - Latest version
128gbRAM, separate 2TB SSD drive solely dedicated for only VSL products. Logic Pro - latest version.