Massive performance issues with small craft

[Zeiss Ikon]

I'm running a barely-modded KSP 1.3.0, without Steam, on Ubuntu Mate 16.04.3 LTS.  The computer this runs on is a Thinkpad T430, Core i7 (dual core) 2.9 GHz (w/ turbo to 3.4 GHz), 8 GB RAM, Intel graphics, and a platter hard disk with more than 100 GB free space in the /home partition.  I also run, simultaneously, MilkyWay@Home, though with its "nice" priority setting it should release clock cycles and appear never to be there except for the small amount of RAM it uses (less than 1 GB).

My mod list:

Better Burn Time.

I've noticed yellow clock routinely, since installation, with vessels as small as 30 parts.  That seems to be about normal for a machine in this clock speed range.  Today, however, I noted that from time to time the yellow clock would completely stop incrementing for up to fifteen or so real time seconds at a time.  At the same time, my vessel (a 25 part space plane, flying approximately level, over open ocean out of sight of land, on jet power at around 200 m/s) would completely freeze, ignoring control inputs, though the altimeter would continue to count up or down and sound (wind noise and the whistle of the Wheesley engines) played uninterrupted -- setting this apart from the stuttering sound that accompanies liftoff in a vessel with too many parts.

I've noticed that my performance in this save (my first career, and the only save I play regularly at this time) has been going downhill over time, but this is ridiculous.  What information is needed to determine and correct the problem?

 

Edited November 27, 2017 by Zeiss Ikon

[Zeiss Ikon]

It appears this was never a KSP problem; somehow, my computer's power management system had been switched to "Power Saving" for all four (two real, two virtual) cores.  In Power Saving mode, the CPU cores are run at the lowest possible clock for the task(s) at hand, in order to reduce energy consumption.

This may have occurred when I was trying to stretch battery life before buying higher capacity batteries.  To be clear, I don't generally play KSP on battery, but there doesn't seem to be a way (in MATE) to set the system to automatically switch from Performance mode when on AC power, to Power Saving mode when on battery -- in fact, the only place I've seen where I can change this setting is in the CPU clock monitor(s) that I have mounted in the system bar.  I'm off now to ask on an Ubuntu support site whether automatic mode switching is possible.