When the CPU load of the encoder is (to) high, the reason is often an infection by a Botnet Attack.
The infected software consumes additional CPU load and the total CPU load is more than you are used to.
Even when there is no video to stream, the CPU load of the encoder can be 40% or more.
The encoders are designed for CCTV systems.
CCTV is the abbreviation of Closed Circuit TeleVision.
The CCTV systems should be separated from the world like internet or other public systems to avoid attacks or manipulation from public networks.
Advise: When using the encoders in public networks, use different usernames & passwords than default.
Have it changed not only for the web page, also for the Telnet and other Linux ports.
And reboot the encoder.