here is a folder with 13000+ subfolders in google Drive File Steam。
but I can't Open it，it will loading，just loading hours and hours，
but in Explorer，I can open it immediately
Is the folder tree turned on? (The screenshot is too cropped to tell.) If so, please try turning it off to see if that makes a difference. (If it does, there are some other settings to try to work out exactly what's going on, but it's the most likely cause of extra overhead, especially if it's looking for archive files and opening all the potential ones.)
If you link your account and send us some process snapshots of when the folder is being read we may be able to use those to see what's happening.