Why is HttpClient slow?

Question

C++ / C#

I am writing a desktop application to work with Google.Drive. I'm using the Google API. Problem with uploading files to the cloud. When uploading, the file is divided into 4 MB chunks. Each chunk is sent as a separate HttpRequestMessage. The HTTPS protocol is used.
The speed is very small, but stable - 600 Kb / s with a channel of 6 Mb / s. Increasing the chunk size doesn't really help.

Wireshark shows this:

Each chunk is divided into a huge number of small TLS packets of 4000 bytes, and a TCP ACK is expected for each packet.
I'm running a Fiddler proxy with the Https capture option (but no reuse client / server connections options). The speed rises to the limit of the channel. Wireshark at the same time shows that at first a huge number of TLS packets are sent almost instantly without waiting for a TCP ACK. Then comes a bunch of confirmations and everything repeats for the next chunk.

Checked on 5 PCs with Win7 - slows down. I tried it on a PC with Win10 - the speed was 10 times higher.

Questions:
1. Is it normal that System.Http.HttpClient breaks each chunk into such small fragments? Is it configured somewhere?
2. How can I speed up the sending of chunks without running Fiddler?
3. Is it possible to force HttpClient to divide a chunk into larger fragments?

Answer 1

For which venda do you write, what SDK do you use? Sample code needed.
For example, in Win RT SDK it is not recommended to use httpclient to download/upload files larger than a few kilobytes.