How to test ffmpeg for streaming encoding at 1x?

I would like to test ffmpeg for encoding a stream on my VM to see how much CPU % it uses, and how many cores. I don’t have streams going, but I plan to use webcams to provide the stream in the future. How should I go about doing this?

I have test mp4 files I could provide.

Should I:

Is there a way to tell ffmpeg to only encode at 1x speed (ie only do 30fps per second for encoding)?
Or do I have to create a stream first and have ffmpeg encode the stream? I found SRS (Simple Realtime Server) github.com/ossrs/srs. I was going to start a stream from there and have ffmpeg ingest it. But it seems complicated I was wondering if there was an easier way by doing #1? Or is there an easier way to do #2?
So far I have tried to get ffmpeg running, but have encountered some errors. The SRS is complicated to setup, so I have not tried it yet.