LinuxCNC on Raspberry Pi 5

I fail how your last post explains what I questioned.

If you want to delve into industry standard, what ever that may mean, you'll have to realise that the RPi isn't certified for industrial applications.

Furthermore I'd like to see the reference to that quote. None of it makes sense. It would appear you chose the wrong hardware setup for for application. Did you realise max step rate was related to latency and therefore the base thread ?

The thing is if you had of asked you would do have been advised on the limitations of software step generation. It's not a finding, it is something that is known. And I could have directed you on how run 7c81 firmware on a $40 spartan 6 dev board, or been directed to one of the other projects.

sudo chrt 99 ping -i .001 10.10.10.10 -c [count I am testing]

sudo ping -i 0.001 -c 1000000 -f 192.168.1.1

This was pinging my router, for about 15 minutes, and I did not get a failed packet, no lockups.

I'm sorry if my previous post was hard to understand or based on misread info. 

I was under the assumption that the most affordable mesa card for 6 axis (5 move and 1 extr) was around 200 bucks. But you are totally right better to ask than assume... I'm sorry for sounding stupid.

I'm still very much open to guidance for hardware selection for my 5 axis printer

Have a great day!

If you had of read the docs, the parts regarding using a parallel port and software step generation, you would have learnt that there is a limit to the stepper speed based on the latency of the base thread.
This is the problem, people don't fully research/read the docs and don't fully understand what they are doing. They also assume things that are not so.
Many times people blame Linuxcnc, 99% of the time it is a mistake they have made.
The recent rise in the availability of home CNC machines has led people to think it is easy thing to setup and use. It's not, there are many hats you have to wear. And to be fair the basis for a project for Linuxcnc, all those years ago, was for control of industrial machines. I don't think the original authors of the papers imagined the extent that small CNC machines would become available to the "average Joe".
Checkout the mesa website, see what they have available. Read the forums, see what other people are doing. Checkout the remora project, have a look at Linuxcnc-RIO, geesh I even gave a link to my own GitHub project.