S3 and S3 Compatible slow upload

Why upload to S3 and S3 compatible cloud are soooo slow? I’m also using a competitors product alongside RaiDrive and upload is much faster. I’m using Amazon S3, Backblaze S3, Dell EMC S3.
RaiDrive ~100kbps
Other product ~1000kbps

Hi~ @Grzegorz_Wozniak,

Small files may be slow because they are uploaded sequentially through several steps.
Could you please tell us what other products you compared?
And if there is an error in the log file(C:\ProgramData\OpenBoxLab\RaiDrive\log), please send it via email(support@raidrive.com). We will tell you again after checking.

I’m using WebDrive and it’s much faster. But I’m not trying to send small files, I was trying to upload one 400MB file.