Arbitrum Ditches Timeboost, Rolls Out Priority Gas Auctions

Arbitrum has ditched its Timeboost transaction ordering system in favor of Priority Gas Auctions (PGA), a model that allows users to compete for execution priority on every single transaction. The change went live on September 24, marking the end of a system that had only been running since April 2025.

The new PGA system works by letting users set a maxPriorityFeePerGas value on individual transactions, which are then evaluated in rapid-fire 125-millisecond rounds that fit inside 250-millisecond blocks. This approach is different from the old Timeboost model, where users participated in sealed-bid, second-price auctions to secure priority over a chunk of time.

The PGA system also includes an 'anti-starvation mechanism' that ensures transactions with low or zero tips don't get permanently stuck at the back of the line. This mechanism guarantees they will eventually be processed.