Om nom nom nom. Oh, and yes, we’re very much aware that a parsec isn’t a unit of time, but of distance.
Solo was not referring directly to his ship’s speed when he made this claim. Instead, he was referring to the shorter route he was able to travel by skirting the nearby Maw black hole cluster, thus making the run in under the standard distance. By moving closer to the black holes, Solo managed to cut the distance down to about 11.5 parsecs. [Source]