Configuring nighthawk-client not to reusing session makes results 10 times worse (and utilization of w CPU/RAM assign to nighthawk server is very low less than 10% )

*Title*: Results for nighthawk client configured not to reuse the session are 10 times less (and utilization of w CPU/RAM assign to nighthawk server is very low, less than 10% )

*Description*:
Command used to run nighthawk:
``nighthawk_client -p http2 --max-requests-per-connection 1 --address-family v4 "https://:" --concurrency auto --rps "1000" --connections "$10" --duration "60" --request-body-size "400" --transport-socket '{"name": "envoy.transport_sockets.tls", "typed_config": { "@type":"type.googleapis.com/envoy.extensions.transport_sockets.tls.v3.UpstreamTlsContext","max_session_keys":"0"}}'
``

When the paramater --transport-socket is not passed, we have noticed 10 times better results and almost 100% utilization of CPU assigned to nighthawk_server. We would like to run nighthawk in a way that client is not reusing the session, parameter max_session_keys":"0" configured that.

*Reproduction steps*:
Run nighthawk with parameter:
``nighthawk_client ... --transport-socket '{"name": "envoy.transport_sockets.tls", "typed_config": { "@type":"type.googleapis.com/envoy.extensions.transport_sockets.tls.v3.UpstreamTlsContext","max_session_keys":"0"}}'
...``
force Nighthawk client not to reuse session, but makes result very low and Nighthawk_server almost not working