Do not disable the cache. You don’t have a bandwidth problem but you are probably not within 1 ms of latency of the Google Drive endpoint, so this would affect performance probably in an unacceptable way, see:
I certainly don’t like the idea.
If you delete the cache and than make a single backup, is the cache already that big or does it grow to this number of time?
You could delete the cache after every backup run, this is till better than running with --no-cache as per the thread linked above.