What is the problem?
I am confused about rpi4 support and performance, I would like to know if a raspberry pi 4 4GB can handle two printers and two webcams
What did you already try to solve it?
Did some research on rpi 4 performance
serial.log or output on terminal tab at a minimum, browser error console if UI issue ... no logs, no support!)
Additional information about your setup (OctoPrint version, OctoPi version, printer, firmware, browser, operating system, ... as much data as possible)
It is not officially supported, so you will not get a lot of help if you run into trouble.
Personally I'm using the PiA+, 1 on each of my printers. Monoprice Mini v.1 and Creality Ender3 Pro.
My primary OS on my PC is Ubuntu 19.04. I am running Cura 4.3 works great. The filename of each sliced file has a prefix to either printer. Setting up a set of folders for each one must be disciplined. I like it. I upload the gcode file into either pi. One has 32gb msd, the other has a 16gb msd. I suppose space for gcode files may eventually be an issue. I keep my files on a 750gb external USB3 Drive.