Running Viz 2019 SP2 at the moment, but this has been an issue for me for a while now.
When I'm working on a project with source geometry from a Solidworks assembly and then try to update/reimport the models, Visualize just sits there doing nothing. Sometimes, it does _almost_ nothing, which is still enough to eventually finish reimporting the model. The time scale I'm talking about is 2-8 hours for a simple assembly with maybe a dozen components and under a million polygons. The whole time, the CPU sits nearly idle (Visualize never gets over 10%), as do the memory and storage. Initially importing the SW file takes under a minute.
What's going on here?