Low internet speed when connected to openconnect vpn

I set up openconnect on vyos 1.4 on vm on a dedicated server, without any shapers. The speed test on a vyos shows ~1Gbps, on a laptop without a connected vpn - ~250 Mbps, with a connected vpn - 80 Mbps. Where can be problem?

Which Speedtest servers are selected for different tests?
Which ones on VyOS, which ones on clients (in both cases)?

since there is no built-in tool for checking speed on vyos, I use a script
curl -s https://raw.githubusercontent.com/sivel/speedtest-cli/master/speedtest.py | python-
and PuhHosting is selected automatically for the test on vyos and on client

What speeds does the host show if you disable OpenConnect, and select the PuhHosting server?

To test the speed directly between Linux devices you can use for example the tcpdump utility.