Why does TLC gzip default to 'off'?

[tangruize]

I found gzip option saves about 88% disk spaces of state files (all-number named files, and overall is about 80%). And the performance loss (states found in 10 minutes) is less than 0.6%. I just test it for about 12 minutes and I don't know the result of the long run.

The TLA+ Toolbox does not have a gzip check box, and I found the gzip option was set to on by default and changed to off after a certain point.

Why does it default to off? Is gzip a good option for performance?