latency test issues

I'm trying to run Linuxcnc on a laptop. I know its not suggested. I have a few questions before I give up on using a laptop. Why is it not suggested? Also I run the latency test using the laptop and and older version of EMC2 with great results (7500ns). I downloaded the newest version of linuxcnc using debian. Trying the test with the new version and I get 1200000ns. Why is this? Also is there anything I can do to improve the latency test on this laptop? As a side note the older versions are using Ubuntu as the OS. Any helpful suggestions and or comments welcome. Thank you

What do you intend to use it for?
Not recomendet because they have a lot of power saving features, like reducing procesor clock, seting it ro idle, bus frequency, serila ATA power saving etc etc, all of that is not good for controling a machine.
Some can be used with a bit of tweaking, some are unusable.
If you can live with older versions of Lcnc all is good ( mostly ).
Also test the preempt-rt kernel version.

I plan to use it to control a Bridgeport series one retrofit. Is there a way to know and fix what is causing the issues? Can I download older versions but not 8-10 years old? If I can download them where would I get them? What is preempt-rt kernel version? Thank you for your time.

Anyone have any ideas? Where can I download older versions of linuxcnc?

linuxcnc.org/iso/
All the old versions in one place.