Some providers, B2, Idrivee2, JottaCloud and S3 (AWS version) needs a checksum for the content.
To calculate this content the libraries will calculate the hash by reading the stream. But since the stream can be throttled, the hash calculation is throttled.
In some cases the contents are buffered, so the transfer is done at full speed, but the hashing at throttled speed. The average speed is the same, but network traffic is bursty, which it should not be with a throttle.
Also added option to disable signing with AWS Sigv4 as that interferes with the throttled stream. It is not currently possible to pass the sha-256 hash to the Sigv4 code, so it will always read the entire (potentially throttled) stream before sending the contents, causing unwanted delays. Use the new option `--s3-disable-payload-signing` to disable v4 signing.