The Mempool
Every transaction passes through a mempool before a block producer picks it up. How it gets prioritised depends on the chain. Toggle between fee-market and deterministic-fee mode to see the difference.
Two regimes, one queue
Bitcoin and most UTxO chains run a fee market. You bid against everyone else. Higher fees jump the queue, low-fee transactions can sit there for hours when the chain is busy. Wallets estimate the going rate so users don’t under- or overpay.
Cardano took a different route. Fees are deterministic: fee = a·size + b, with protocol-set constants a ≈ 0.000044 ₳/byte (per byte) and b ≈ 0.155 ₳ (constant). There is no bidding, no “tip the miner,” no surprise fee spikes. Two identical transactions cost the same, always.
Why eUTXO mempools differ structurally
On account-model chains, two transactions touching the same account contend for the same nonce — only one can land. On eUTXO, two transactions only conflict if they spend the same UTxO. Independent transactions can be included in parallel without ordering constraints, so the mempool dynamics are fundamentally different even before you get to fee-market questions.
Three quick questions
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