Hey, I've been using Mach3 for a few years now and have been having this problem the whole time, but only with large cuts.
The PC and CNC machine will constantly pause / go / pause / go. It's almost as if the PC has to wait for the CNC to complete each action before if feeds it the next line of code. This only happens on designs with large amounts of code. All smaller designs have run just fine, without any of these pausing issues.
I have tried using a newer PC, with more ram and much more powerful CPU, which reduces the pausing, but does not eliminate it.
Any advice or assistance would be greatly appreciated.