Across Prime

Across Prime is a proposed trustless fast bridge design that replaces the escrowed model used by Across with a bonded model, which the article says is significantly more capital efficient while keeping most of the security and decentralization benefits. In the bonded model, the relayer receives the user's payment on the origin chain immediately, and a security deposit determines the maximum amount the relayer can have in flight at any time. The article's example assumes a $1,000 bond, two-second blocks on both chains, and a one-hour settlement oracle, and it estimates up to $900,000 in hourly bandwidth, which it says makes the bonded model up to 900 times more capital efficient than the escrowed model under those assumptions.