Diamond: Place and Route: Timing: When the PAR (Place And Route) property auto hold-time correction is set to On, the router automatically inserts extra wires to compensate for the hold time violation on affected registers. Internal hold time failures are a common and can be hard to debug as a result auto hold-time should always be enabled. Reasons for disabling it might be to get a better setup time or to get a quick run time through PAR.