Earth's orbit
Halley's Comet on an eccentric orbit that reaches beyond Neptune will be moving 54.6 km/s when from the Sun, 41.5 km/s when 1 AU from the Sun (passing Earth's orbit), and roughly 1 km/s at aphelion from the Sun. Objects passing Earth's orbit going faster than 42.1 km/s have achieved escape velocity and will be ejected from the Solar System if not slowed down by a gravitational interaction with a planet.