Other than custom framerates, downscaling texture quality, disabling anti-aliasing features, using another lighting engine, and using an older rendering engine, I don’t think these flags are really that useful in any kind of legitimate usage.
Lots of said “performance-improvement” flags could also introduce unfair advantages, and sometimes be used for cheating too, such as:
- Disabling blur / post-processing effects
- Reducing mesh/union quality by forcing LoD (level of detail) to the lowest level
- Disabling shadows