1. The FIFO Execution Model and MEV Mitigation

Cardano’s First-In-First-Out (FIFO) execution model significantly mitigates the most common user-facing MEV (Maximal Extractable Value) attacks, such as front-running and sandwiching, but it does not "solve" MEV entirely. Instead, it shifts the competition from a fee-based auction (gas wars) to a latency race, where speed and network proximity to validators determine who extracts value.

1. The FIFO Execution Model and MEV Mitigation

Cardano utilizes a deterministic fee model where transaction costs are calculated based on a fixed formula ($a + b \times \text{size}$), ensuring users know the cost before submission [Source: https://www.bankfrick.com/]. Because there is no native "priority fee" or "tip" field to jump the queue, transactions are processed in the order they arrive at the block producer.

2. The Shift to Latency Wars

While FIFO removes the incentive for users to outbid each other, it creates a different set of MEV challenges:

• Latency-based MEV: Value is extracted by actors with the fastest network connections to Stake Pool Operators (SPOs). This favors sophisticated bots over average users.
• Validator Discretion: A malicious SPO could theoretically reorder transactions within their own block to favor their own trades, as they are the ultimate authority for that specific slot.
• Spam Vulnerability: Because fees are low and fixed, attackers can attempt to "DDoS" the mempool with cheap transactions to ensure their own transaction is the one that gets through during a high-value opportunity.

3. The Introduction of Priority Fees (Tiered Pricing)

To address the limitations of pure FIFO—specifically the risk of critical transactions being delayed during congestion—IOHK has proposed a Tiered Pricing model [Source: https://iohk.io/en/blog/].

• Fair Tier (50% of block): Maintains the current FIFO, low-fee structure.
• Immediate Tier (20% of block): Introduces a "fast lane" where fees react to demand. This effectively reintroduces Priority Fees to Cardano.
• Impact: While this ensures network stability and allows urgent transactions (like oracles) to pass through, it also reintroduces the potential for Priority Gas Auctions (PGAs) within that specific portion of the block.

4. Status of Research Claims

• c1 (FIFO Model): UNRESOLVED. While research confirms Cardano uses a non-prioritized model, the specific technical implementation of FIFO across all node versions remains a subject of ongoing documentation updates.
• c2 (Elimination of Priority Fees): RESOLVED. Cardano's current architecture does not require priority fees for transaction inclusion, relying instead on deterministic fees [Source: https://www.bankfrick.com/], [Source: https://cexplorer.io/].
• c3 (Solving Front-running/Sandwiching): UNRESOLVED. While these are "highly mitigated," the claim that they are "solved" is contested due to the potential for validator-level reordering.
• c4 (Latency Wars/Limitations): UNRESOLVED. The shift from fee-based competition to latency-based competition is widely discussed in the community, but formal protocol-level metrics on latency-based extraction are still being established.

Conclusion

Cardano's FIFO model solves the unpredictable cost and sandwiching issues prevalent on Ethereum, but it replaces them with a latency race. The proposed move toward tiered pricing suggests that a pure FIFO model is insufficient for a congested network, leading Cardano to adopt a hybrid approach that includes a form of priority fees for urgent transactions.

Next Steps:

• Would you like to see a technical analysis of how Cardano's Tiered Pricing proposal compares to Ethereum's EIP-1559?
• I can research the current status of Babel Fees on Cardano to see how they might impact MEV and transaction prioritization.