Improve FrameServer performances

I followed ffmpeg guide to install debugmode frameserver.

All works fine except with the fact that the frames served does not goes up to 25 fps. FFmpeg reports a speed of 0.9x..

My initial goal would have been use ffmpeg for encode very fast instead using native NLE export..

I would have expected something like 50x ! How can I improve the performances of the frameserver? The signpost avi is on a NVME professional drive.

There are other frameservers compatible with AviSynth that I can use instead of the debugmode one?

The string I used is:

ffmpeg -y -i D:\frameserver_test\frameserver.avs -map 0 -c:v libx264 -preset ultrafast -b:v 3000k -c:a copy D:\frameserver_test\out.mov 

while frameserver.avs contains:

AviSource("D:\frameserver_test\output.avi");