Tips for improving SwiftUI Preview performance?

I'm working on a medium-ish sized project with a few 3rd party dependencies. SwiftUI previews are basically becoming unusable at this point. Any minor modification can result in 30-90 second delays to seethe preview update. What have ya'll tried that improves the preview performance? I've read that modularizing your code into separate frameworks may help, but wanted to see if anyone had actual experience before going down that path.