I have a relatively large library with about 1500 films and 13000 TV episodes on Google Drive (almost 36TB). The first sync with Infuse took a few hours, but the updates were relatively quick, from 1 to 2 minutes to identify new content and start generating metadata.
From two or three updates up until now, however, this search for new content is extremely slow. If before I waited a maximum of 2 minutes, now it reaches 20. And this is just to identify new content.
My Google Drive remains with the same folder organization as before and I use Infuse on iOS only (iPhone and iPad) always using the latest official version of the App Store.