Google to one drive cloud sync too slow

Correct!

The important thing to understand about both OneDrive and Google Drive is that they are priced per size only and therefore both come with limitations to the speed and number of requests you can do within an hour/day (that is fair usage limitations that are enforced by some kind of rate limiting or throttling).

If you want unlimited speed and up/download capacity, then you typically get to pay per request (one way or the other).

You may find this thread/post interesting:

I may be completely wrong, but your large amount of data stored in 100GB files indicate that you also may find this Backblaze blog post interesting: