No, XPages are not in use.
The weird thing is that the CPU is not being overused, it's only the RAM.
All agents have been disabled.
The server is usually OK but starts acting up on the following day.
I suspected that it was something running at night or early morning.
In the end, what solved our problem was to disable scheduled tasks, namely Updall, which was running at 2 in the morning.
Thanks a lot Mike and Scott for your help and advice.
Feedback response number WEBBB2X8F3 created by Nad Surf on 07/23/2018