RHEL 8 SFTP high cpu

We has setup RHEL 8.x server with 2 CPU, 8GB Memory.
Configured SFTP service on this and noticed high cpu usage(almost 100%) with just 5 concurrent connections/sessions. We just used the default configuration with internal-sftp.

There was some discussion regarding ftp protocol speed. And someone mentioned encryption/decryption uses 1 core all the time. Is that true?

https://serverfault.com/questions/559501/ftp-ftps-sftp-scp-speed-comparison/559934

How to get the good performance with above specs.