Performance and Image Quality are related and have a button to quickly jump between the two settings.
Verification on rebuild causes each face in a model to be checked against all other faces in the model. When this option is cleared, each face is checked only against the surrounding faces. While it is important to make sure that you have a good model by using Verification on rebuild, you do not have to leave it on all the time. Instead, turn this option on periodically and do a forced rebuild (Ctrl+Q) to make sure the model builds without errors. Then clear the option. This allows you to work faster but also to check your models to avoid a catastrophic error.