Ah, I wasn't aware of that.
It is written in Javascript so I will never be able to get the same performance as e.g. ffmpeg. But I have been optimizing the code over and over again, so I had hoped that it would be at least usable... Especially since the ESP32 cam seems sends the Content-Lenght (i.e. the length of the image byte buffer) withing the stream: then my node just can copy entire images, without having to search for boundaries between images (which should be very fast).
Perhaps this is a bit off-topic, but what do you mean with "fps is decreasing significant"? I always put an node-red-contrib-msg-speed node in my flow when I want to measure the fps ...
Since I only use my own multipart decoder node for decoding mjpeg, I have no experience with other nodes. In that case you might have a look at the proposal from @kuema above...
Sorry to hear from your boat accident. But beside that, it is always nice to hear in which use case our contributions are being used 
