Not sure if it grows faster, but it certainly grows fast! I cut branches off mine last spring and stuck them in the ground and by fall one of the 'sticks' even bloomed! Also, it stays where it is put instead of suckering like forsythia.

Look into chaste trees (vitex). Lazy S Farms has several different varieties. You can keep them as a bush by cutting them back to the ground every year or you can prune them as trees. They bloom for months and remind me of a butterfly bush with the type of blooms. Love, love. Easy and very versatile.

You are on the edge of the zone for chaste trees, but I have read several people that were successful with them in zone 5.