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TimeBoost is Arbitrum’s priority sequencing auction that grants the winner a 200ms express lane advantage over the public mempool. This is a key differentiator for the platform — the agent can bid for express lane access, execute priority trades, and resell unused capacity for profit.

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What Is TimeBoost?

TimeBoost is Arbitrum’s answer to MEV. Instead of a first-come-first-served mempool, Arbitrum runs a sealed-bid, second-price auction every 60 seconds. The winner of each round becomes the express lane controller and can submit transactions that get sequenced 200 milliseconds before any public mempool transactions.

60-Second Rounds

Each auction round lasts 60 seconds. Bids must be submitted at least 15 seconds before the round starts.

Sealed-Bid Auction

Bids are private. You pay the second-highest bid, not your own — incentivizing truthful bidding.

200ms Priority

The express lane controller’s transactions are sequenced 200ms ahead of public mempool transactions.

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Why It Matters

The 200ms priority window creates a structural advantage for:
  • DEX arbitrage: capture price discrepancies across Uniswap, Camelot, and other DEXs before other traders
  • Liquidations: be first to liquidate undercollateralized lending positions on Aave, Radiant, etc.
  • Backrunning: execute profitable backrun trades on large public mempool transactions
  • Priority execution: ensure your time-sensitive trades execute before competitors
On Arbitrum, TimeBoost replaces traditional block builder MEV extraction. The revenue goes to the Arbitrum DAO treasury rather than to individual block builders, making it a fairer system overall.

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How the Bidder Works

The TimeBoostBidder class manages the full lifecycle of express lane participation.

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Bid Loop

When started, the bidder runs a continuous loop:
  1. Detect round transition — polls the auctioneer for the current round number
  2. Estimate round value — calculates expected MEV profit from available strategies
  3. Compare against threshold — skips rounds where expected profit is below minProfitThresholdWei
  4. Fetch auctioneer stats — gets the average winning bid to avoid overbidding
  5. Submit bid — places a bid at 80% of expected profit, capped at 90% of the average winning bid
  6. Wait for result — if won, emits roundWon event; otherwise emits roundLost

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Bid Submission

Bids are submitted via JSON-RPC to the autonomous auctioneer: 
Method: auctioneer_submitBid
Params: {
  chainId,
  expressLaneController,
  auctionContractAddress,
  round,
  amount
}
The auctioneer only considers the most recent bid per address, so the bidder can update its bid as new information arrives before the auction closes.

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Express Lane Transactions

When the bidder wins a round, it can submit transactions via the express lane: 
Method: timeboost_sendExpressLaneTransaction
Params: {
  round,
  sequenceNumber,
  transaction,
  auctionContractAddress,
  signature
}
These transactions are sequenced by the Arbitrum sequencer with 200ms priority over the public mempool.

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MEV Estimation

The bidder estimates the expected value of each round using a per-strategy model with historical calibration.

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Strategy Values

StrategyEstimated ValueDescription
arb~0.002 ETHCross-DEX arbitrage opportunities
liquidation~0.005 ETHLending protocol liquidation profit
sandwich~0.0015 ETHSandwich trading (higher risk)
backrun~0.0008 ETHBackrunning large transactions
resale~0.003 ETHExpress lane resale revenue

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Historical Calibration

The bidder maintains a rolling history of the last 100 round outcomes. This history adjusts the estimation multiplier:
History SignalMultiplierEffect
< 5 rounds of data1.0xNeutral (no data)
Average profit negative0.6xReduce bid aggressiveness
Average profit > 0.005 ETH1.2xIncrease bid aggressiveness
Otherwise1.0xNo adjustment
The bidder also subtracts estimated gas costs (~0.00002 ETH on Arbitrum) from the total expected value before placing a bid.
Call bidder.recordRoundResult(round, profitWei) after each won round to feed the historical calibration system. More data leads to more accurate bid sizing.

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Express Lane Resale

A key revenue multiplier: if you win a round but do not need the full 60 seconds of express lane access, you can resell capacity to other searchers.

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How Resale Works

  1. Win an express lane round for cost X
  2. Other searchers pay you USDC via x402 micropayments for sub-round access
  3. The resellExpressLane(buyer, pricePaidUsdc) method grants the buyer express lane forwarding rights for the remainder of the round
  4. Multiple resale slots can be active simultaneously within a single round

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Revenue Model

The total revenue from a won round can come from three sources:

Direct MEV

Profit from executing priority arbitrage, liquidations, and backruns during the 200ms window.

Resale Revenue

USDC payments from other searchers who buy sub-round express lane access.

Skill Execution

Other agents pay USDC to use the express lane as a paid skill via the MCP server.

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TimeBoost Vault Contract

The TimeBoostVault Stylus contract manages the financial infrastructure for bidding and resale:
  • Bid funding: agents deposit ETH or USDC that the vault uses for auction bids
  • Resale payments: authorized buyers pay USDC to the vault in exchange for express lane transaction forwarding
  • Earnings tracking: the contract tracks total_resale_earnings and total_bid_cost for P&L calculation
  • Owner withdrawal: accumulated profits can be withdrawn by the vault owner
The TimeBoostVault is a Stylus contract written in Rust. It manages the USDC payment flow for resale but does not directly interact with the auctioneer. The off-chain TimeBoostBidder handles bid submission.

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Auctioneer Stats

The bidder can query aggregate auction statistics to inform bidding strategy: 
const stats = await bidder.refreshAuctioneerStats();
// stats.avgWinningBidWei — average winning bid over recent rounds
// stats.recentRounds    — number of rounds in the sample
// stats.winRate         — our win rate percentage
Stats are cached for 5 minutes to avoid excessive RPC calls.

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Risk Factors

TimeBoost bidding involves real financial risk. Consider these factors before enabling automated bidding.
RiskDescription
OverbiddingBidding more than the MEV you can extract leads to losses
Execution riskWinning the round does not guarantee profitable MEV execution
CompetitionSophisticated searchers dominate most rounds
Capital lockupBid capital is committed for the round duration
Gas costsFailed strategies still consume gas

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Configuration

The TimeBoostBidder accepts these configuration options:
OptionTypeDefaultDescription
privateKeyHexRequiredSigning key for bids and express lane txs
rpcUrlstringArbitrum One public RPCArbitrum RPC endpoint
auctioneerUrlstringhttps://arb1-auctioneer.arbitrum.io/TimeBoost auctioneer RPC endpoint
minProfitThresholdWeibigint0nMinimum expected profit to place a bid

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Example Usage

Enable TimeBoost bidding with a 0.001 ETH minimum profit threshold

What's the current express lane status?

How many TimeBoost rounds have we won this session?

Resell express lane access at 5 USDC per slot