In QGIS 3, What's the difference between "Do not filter (better performance)" and "Ignore invalid geometries"?
Both can be found at Settings > Options > Processing > General
Both are options to ignore invalid geometries during spatial analysis.
"Ignore invalid geometries" is poorly worded -- this option should be "Skip features with invalid geometries". Selecting it causes those features to be skipped over, just like they don't exist.