Need some assistance understanding my Latency Test result

I just purchased a renewed HP ProDesk 600 G1 SFF for my wife to work remotely and I wanted to see if it will work for LinuxCNC since it was stupid cheap. Here are the basic specs:

• Processor: Intel Core i5-4570 3.2 GHz Turbo 3.6 GHz
• Memory: 16GB DDR3
• Storage: 500GB HDD
• Optical driver: DVD
• Port: USB 3.0, DisplayPort, VGA, RJ-45.
  
  I purchased the Mesa 7I76E Motion Control Board so I will not be using Parallel Port. 
  When I ran the test I was surprised at how high the Max Jitter number are. The Base Thread looks good from what I have read but not sure what to do about the Jitter numbers. 
  
                                     Max Jitter (ns)
  Servo thread (1ms):     3,284,972
  Base thread (25µs):    10,108,437
  
  If these numbers are a problem what can I do to get them in line? 
  
  Thanks,
  Shawn

In BIOS disable:
Hyperthreading
C states
Virtualisation
Turbo
Speedstep
Anything power saving

Also make sure you are running a real time kernel with:

uname -a

This PC has very few options in the bios but I turned off everything that appears power saving.

Nothing really changed. I am still right at 10,000,000 Jitter. Is there anything else that I should try?

Here are the results of uname -a:

Linux debian 4.19.0-17-rt-amd64 #1 SMP PREEMPT RT Debian 4.19.194-2 (2021-06-21) x86_64 GNU/Linux

From what I can tell the kernel is a real-time (RT) kernel, although maybe a little old as I downloaded it maybe 9-12 months ago.

I am kind of feeling like this PC may be a bust. Maybe I should be looking at other options? I just started researching the mini PC market because I have read that others have had good luck with some of them. I am not real sure what to look for exactly.

From what I have learned reading through tons of posts is fewer cores is better, no hyperthreading (although can be turned off), processor base frequency above 2GHz (or is it burst frequency? can't remember). What else should I look for/not look for?

Would a Celeron (dual-core w/base frequency of 1.1GHz) be better than a I5 (dual-core/4 thread w/base frequency of 2.9GHz)? All the Celerons and the like seem to have a low base frequency.