s3 multipart uploads

Could you guys please improve the S3 interface to use multipart uploads?
It's a great tool you have here, I love it, but the upload speeds are magnitudes lower than my upload bandwidth limit. Uploading a large backup file (tens of GBs) is taking 8-10 hours.

Thanks!

p.s. I wanted to donate again (as I did a long while back but it must have been on another account as it does not show), but paypal has shat itself for me, and they've no support - it'd be great if there was another method for payment.

Thanks for your suggestion.
We will see, if more people ask for this.

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https://winscp.net/eng/donate.php