Download RBI is slow with HTTP(S)

We moved away from S3 protocol to switch to HTTPS instead (but still on S3).
This removes a glue to S3 but HTTP download is much slower even with a very good bandwidth (we have a 1Gbps fiber optic connection here and I can barely get more than 5~10 MB/s download.
With direct S3, I could go as high as 90 MB/s so basically 10x times more.

Can we get back to S3 or use multipart HTTP downloads instead ?