Tools > Options > Performance and set level of detail to Off (for no detail) or More (slower)
Can't reproduce here .
Close all files and then try to set level of details.
I can set that even with files opened. You can set the level as per you need. You can set to some value, check and then set accordingly to reach to a satisfactory level.
For Curvature Generation
Only on demand. Initial curvature display is slower, but uses less memory.
Always (for every shaded model). Curvature displays more quickly on the first display, but extra memory is always used (RAM and disk) for every part that you create or open.
So you need to set it according to memory available in your machine.
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