I've never seen one that does this... in fact, I've seen a few firms that have tried this and the VC's quickly labeled them as "just lead gen" with an unattractive, non-recurring business model.
Granted, you can keep generating performance - but it will arguably continue to cost you a lot of maintain the performance. Thus, the profit margin doesn't increase over time.
There is a firm that focuses on 'contract renewals' and their model is a % of contracts they get to renew. To support their business, they've built a platform that makes it easy to manage/track/renew contracts... so its performance based, but its also technology based with a lot of lock in.
I've *never* seen a VC invest in a creative agency. That is typically reserved for Private Equity firms or specialized banking... and its less about investment and more about buying part of your business (owner liquidation).
Good luck!
