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I'm interested in this as well.  I have spent many hours trying to get > 11-12 m/min smooth motion on a large format router without joint following errors and/or jerky motion.  Using the old control or TwinCAT CNC with the same servo driver config works fine at 30 m/min.

I'm no expert on LCNC internals but if RTAPI_TASK_PLL_SUPPORT is defined in linuxcnc-ethercat lcec_main.c then it appears that syncronization is attempted between the ethercat application cycle and LCNC with a max error of one app period...maybe this is where Hakan is getting the potential extra cycle delay.

Since you have the ethercat master running outside LCNC it seems like it would be difficult for those to be perfectly syncronized but perhaps that does not matter in application. I know TwinCAT is running in hard realtime on one or more dedicated cpu cores outside of operating system and with their tools you can see how much time is being used in each cycle.  It would be nice if there were a tool for LCNC where you could see that info but I'm not sure it's even possible in the current architecture.

after moving the jumper I was able to get the computer to see the device again and I thought I had it programmed but moving the jumper causes it to be not seen again... Not sure where I am messing this up but I will keep reading forums and manuals

Used old Dell Optiplex 980 in Tower version has a built in parallel port, plenty can be found for very cheap, you can probaly just yank the old hard drive and put it in the new PC and everything should work. Granted the hard drive works.