Why are uploads to Google Drive slower than to other destinations?
Short answer: Google limits how fast apps can upload and adds a short delay per file, so big or many-file transfers take longer. It keeps running and resumes if interrupted. For a huge first copy, an external SSD or bucket storage is quicker.
Google deliberately limits how quickly apps can upload, and adds a small delay to each file, so a transfer or first backup with many files can take a long time. It isn't stuck — it keeps going in the background and resumes where it left off if interrupted.
For a very large first copy, an external SSD or bucket storage is usually much faster. After the first run, only changes are sent, so day-to-day use is quicker. See backups for how ongoing backups work.