Why no Mach3 latency problem?

Why does Mach3 not have a latency problem? I'm a newbie so am prepared to be corrected on this. But my new desktop cnc router/mill/engraver came with Mach3 as the setup and test software. There is no mention of running a latency test within the setup. Using the created Mach3 xml configuration file, I have successfully converted this to a linuxcnc stepconf file and the machine appears to behave.
The PC I'm using is dual-booted to both Windows XP and linuxcnc Debian - so the physical PC (motherboard, BIOS, graphics, etc.) is common. So it seems that latency is not really a problem with the PC - but with how linuxcnc interacts with the PC. This is not uncommon with Linux - as many software solutions have to make do with reverse-engineered drivers etc.
I would appreciate forum comments to diminish my naivety.

Mach3 does have a test routine that allows you to check latency at what they call the kernel speed
this is roughly equivalent to LinuxCNC's base thread rate.

Mach3 has the same problems with latency as LinuxCNC.
If there were no latency issue, 100 KHz or even 200 KHz pulse streams would be easy on a PCI parallel port.
This is typically not possible with LinuxCNC or Mach3 due to interrupt latency, though Mach3s
performance may be better or worse than Linuxcnc on specific Motherboards.

LinuxCNC does tend to be a bit more conservative however and warns of run time timing
violations that Mach3 ignores