Small change in clock period leads to wide swing in CTS TNS

[jeffng-or]

Subject

Describe the bug

Found during frequency sweep of asap7 ibex, where a small change in clock period leads to a much wider swing in CTS TNS. @maliberty requested filing GH issue to see if we can drive down the range.

Clock Period	CTS TNS
1001.8 ps	-49915 ps
1009.3 ps	-18862 ps

The overall CTS WNS/TNS chart looks like:

Expected Behavior

Reduced variation in TNS

Environment

b3f8033f64550f9601c8453d2cf7c178d7902133 - orfs git commit tag

To Reproduce

"min" value tarball: https://drive.google.com/file/d/1eAX7XIo6DWB1Y2afe-tg0q_fdV3dVwfW/view?usp=drive_link
"max" value tarball: https://drive.google.com/file/d/1IFMWERyTzKmT9rTYGk26U1r9auk30BAY/view?usp=drive_link

Relevant log output

Screenshots

No response

Additional Context

No response

[maliberty]

This is part of bigger goal to set better metrics limits but tns is so noisy the limit will be very large. Driving this variability down will help us set a more reasonable bound.