QtPlasmaC Jogging Lag

I have noticed that there is a considerable amount of input lag (~0.5 seconds) from when a keyboard jogging key is pressed or the arrows in the GUI are clicked until movement actually starts. I have looked at the movement signals (pos&vel) and cannot tell that anything is wrong after the move actually starts. The max accelerations and velocities are hit, there is just a delay between when the key is pressed and the move actually starts. This is impossible to capture with HALSCOPE unless there is a signal I can tie into that detect the keyboard press, but I have not found one yet. At the current state, it is very difficult, to use the machine as I cannot accurately jog to a spot to set my origin.

One thing to note is that I have a QTVCP based gui (QtDragon-HD) for when I use a spindle with the same machine. All velocities and accelerations are identical and there is no lag whatsoever with that config. QtPlasmaC use to be the same, but I noticed that recently the lag has started. I cannot say the last version for which it worked properly; I tried to build older versions of linuxcnc but ran into compilation errors.

Any ideas on things to try to measure with HALSCOPE or others would be helpful! 

Thanks for your response. Here's some more info:
OS is Mint 19.3
Computer is a Dell Optiplex 960
CPU: Intel Core 2 Duo E8400 @ 3.00 GHz
RAM: 4GB
I use RIP, however I have a buildbot installation as a backup (QtPlasmaC version is v1.0.32)

Now that I notice it, the lag does seem to be across the board. It was hard to notice until I checked the Pulse Torch button (plasma cutter off so I could just hear the relay clicking). Clicking check boxes seems to have the same amount of lag, but it wasn't as apparent as it was when trying to jog.

I loaded up my old buildbot install (again, v1.0.32 QtPlasmaC) and there is no lag at all.

let me know if you want me to run it longer

Latency test
 

Sounds good, I'll keep it running and post the results after a few hours.

I am running a 5i25/7i76 combo.

I may end up nuking the system and starting fresh. I believe I may have screwed some things up trying to update (add) python3.8 as one of the latest builds requires >3.7 and I was only running 3.6.9. I might look into MX as I'm not really tied to Mint, it's just what has been working for me. Are you using xfce or kde?

Is Phill running it on Mint as well?

Is some process using a lot of CPU or memory? Laggy GUI/KB/Mouse response
is often related to resource exhaustion. What does "top" show?

Alternatively, you can side-step all the userland timing issues by using
real hardware buttons/MPGs

With a ~current version of QtPlasmaC (v1.0.76) it is pegged @ 100% CPU usage and laggy.
Running my older buildbot installation QtPlasmaC (v1.0.32), it peaks @ 15% CPU usage and no lag.

Starting my mill config with QtDragon-HD, I'm around 10% usage