Optimistic Rollups (like Arbitrum One, Optimism) excel at minimizing transaction costs during low-load periods because they post minimal data to Ethereum L1 and defer expensive computation via fraud proofs. For example, during non-peak hours, an Arbitrum transaction can cost under $0.01, as it primarily pays for compressed calldata on Ethereum. This model prioritizes low baseline costs, making it ideal for applications like NFT marketplaces or social dApps with sporadic user activity.
LABS
Comparisons
Optimistic vs ZK Rollups: Cost at Low Load
A technical analysis comparing the base transaction cost structures of Optimistic and Zero-Knowledge Rollups under conditions of low network congestion, focusing on fixed overhead, variable fees, and economic trade-offs for CTOs and protocol architects.
Chainscore © 2026
introduction
THE ANALYSIS
Introduction: The Low-Load Cost Equation
Understanding the fundamental cost structures of Optimistic and ZK Rollups is critical for projects with variable or initially low transaction volumes.
ZK Rollups (like zkSync Era, StarkNet) take a different approach by generating cryptographic validity proofs for every batch. This results in a higher fixed computational cost for proof generation, but ensures immediate finality and lower L1 data costs per transaction in a batch. The trade-off is that for very low activity, the cost to generate a ZK-SNARK or STARK proof can be amortized over fewer transactions, potentially raising per-user fees compared to an idle Optimistic chain.
The key trade-off: If your priority is predictable, ultra-low costs for a nascent application with uncertain traffic, an Optimistic Rollup provides a lower-cost floor. If you prioritize security guarantees, immediate fund withdrawal, and scalability for a protocol expecting consistently high batch utilization, a ZK Rollup's cost structure becomes more efficient. Monitor metrics like average batch size and proof generation time (e.g., zkSync's ~10-minute proof time) against your expected TPS to model true cost.
tldr-summary
Optimistic vs ZK Rollups
TL;DR: Key Cost Differentiators at Low Load
At low transaction volumes, the cost structure diverges sharply. Here's the breakdown for teams building or migrating with budget constraints.
01
Optimistic Rollups: Lower Fixed Costs
Minimal proof generation overhead: No expensive ZK-SNARK/STARK proofs are computed for each batch, leading to lower baseline L1 data publishing fees. This matters for early-stage dApps or niche protocols where transaction throughput is sporadic and predictable.
< $0.01
Typical L2 TX Cost
7 Days
Withdrawal Delay
03
ZK Rollups: No Withdrawal Delays
Instant finality via validity proofs: Users and protocols don't need to lock capital for a 7-day challenge period. This matters for high-frequency trading (HFT) DeFi and bridging solutions where liquidity efficiency and user experience are critical, even at low load.
~10 min
Withdrawal Time
High
Prover Cost
OPTIMISTIC VS ZK ROLLUPS
Cost Structure Breakdown at Low Load
Comparison of transaction cost components for a single simple transfer under low network congestion.
| Cost Component | Optimistic Rollup (e.g., Arbitrum One) | ZK Rollup (e.g., zkSync Era) |
|---|---|---|
L1 Data Publishing Fee | $0.10 - $0.30 | $0.05 - $0.15 |
L1 State Verification Fee | $0.00 (Delayed) | $0.20 - $0.40 (Instant) |
Sequencer/Prover Fee | $0.001 - $0.005 | $0.003 - $0.010 |
Total Est. User Cost | $0.101 - $0.305 | $0.253 - $0.560 |
Cost Finality Time | ~7 days (Challenge Period) | < 1 hour |
Data Compression Efficiency | Medium | High |
Trust Assumption | 1-of-N Honest Validator | Cryptographic (ZK Proof) |
pros-cons-a
Cost at Low Load
Optimistic Rollup Cost Profile: Pros & Cons
Transaction cost dynamics differ fundamentally between Optimistic (ORU) and Zero-Knowledge (ZK) rollups under low network utilization. This is critical for bootstrapping dApps and user onboarding.
01
Optimistic Rollup: Lower Fixed Costs
Specific advantage: Minimal proof generation overhead. ORUs like Arbitrum One and Optimism batch transactions without expensive cryptographic proofs, leading to lower baseline L1 data posting fees. This matters for early-stage dApps and prototyping where every cent of user acquisition cost counts.
< $0.10
Typical TX Cost
~24 hrs
Withdrawal Delay
03
ZK Rollup: No Costly Challenge Periods
Specific advantage: Instant finality reduces operational overhead. ZKRs like zkSync Era and Starknet provide validity proofs, eliminating the need for a 7-day fraud proof window and associated capital lock-up costs for bridges/sequencers. This matters for exchanges, payment processors, and institutional users who cannot tolerate withdrawal delays.
~10 min
Withdrawal Time
04
ZK Rollup: Higher Baseline, Better Scaling
Specific advantage: Higher baseline, better scaling. While ZK proof generation (e.g., STARK proofs on Starknet, PLONK proofs on zkSync) has a high fixed cost, it's amortized over massive batches. At sufficient load, ZKRs can become cheaper than ORUs. This matters for established protocols with predictable, high throughput where long-term operational efficiency wins.
pros-cons-b
Cost at Low Load
ZK Rollup Cost Profile: Pros & Cons
Transaction cost structure differs fundamentally between Optimistic and ZK Rollups, especially under low network utilization. This comparison highlights the key trade-offs for teams building or migrating applications.
01
Optimistic Rollup: Lower Fixed Costs
Minimal proof generation overhead: No expensive ZK-SNARK/STARK proofs are computed per transaction, leading to lower baseline compute costs for the sequencer. This matters for prototyping or applications with sporadic, low-volume activity where cost predictability is key. Example: A simple NFT mint on Optimism can cost ~$0.001 in L2 fees.
02
Optimistic Rollup: Withdrawal Latency Cost
7-day challenge period creates capital inefficiency: Users must wait ~1 week for full withdrawal security, locking funds and creating opportunity cost. This matters for high-frequency traders, bridges, or protocols requiring fast L1 settlement. While third-party liquidity providers (e.g., Hop Protocol, Across) offer instant withdrawals for a fee (~0.1-0.3%), this adds a variable, user-paid premium.
03
ZK Rollup: Predictable Finality Cost
Instant finality eliminates withdrawal delays: Validity proofs provide immediate L1 state confirmation, removing the capital lock-up cost and associated liquidity provider fees. This matters for CEX integration, perpetual dexes, and institutional use cases where settlement certainty is paramount. Example: Withdrawals from zkSync Era to Ethereum Mainnet are finalized in ~10 minutes.
04
ZK Rollup: Higher Prover Overhead
Proof generation requires significant computational resources: Sequencers incur high fixed costs for proof computation, which are amortized across a batch. At low load, this cost-per-transaction remains high. This matters for niche dApps or new chains that cannot yet guarantee high transaction volume to dilute the prover cost. Specialized hardware (GPUs/ASICs) for proving adds to operational complexity.
CHOOSE YOUR PRIORITY
Decision Framework: Choose Based on Your Use Case
Optimistic Rollups for DeFi
Verdict: The current standard for high-value, complex applications. Strengths: Arbitrum and Optimism dominate with massive TVL (billions) and a mature ecosystem of protocols like Uniswap, Aave, and GMX. EVM-equivalence means minimal code changes for deployment. Fraud proofs provide strong security for large capital pools. Trade-off: Users face a 7-day challenge period for withdrawals, requiring liquidity bridges like Hop Protocol or Across. Transaction fees are low but not the absolute lowest.
ZK Rollups for DeFi
Verdict: The emerging contender, ideal for applications valuing final speed and ultra-low costs. Strengths: zkSync Era and StarkNet offer near-instant finality (minutes vs. days) and potentially lower fees at scale. Native account abstraction improves UX. ZK-proofs provide mathematical security from block one. Trade-off: Ecosystem is younger with less TVL. Some ZK-EVMs (like zkSync) have minor differences from Solidity, and proving costs can be high for complex, one-off transactions.
verdict
THE ANALYSIS
Final Verdict & Strategic Recommendation
Choosing between Optimistic and ZK Rollups for low-load applications comes down to a fundamental trade-off between immediate cost and finality.
Optimistic Rollups (like Arbitrum One and Optimism) excel at minimizing transaction costs under low load because they avoid the intensive computational overhead of generating validity proofs. For example, a simple token transfer on Arbitrum can cost under $0.01, leveraging the same low-cost data availability as ZK Rollups without the proof-generation expense. This makes them ideal for applications where users are highly sensitive to gas fees and can tolerate the standard 7-day challenge period for withdrawals.
ZK Rollups (like zkSync Era and StarkNet) take a different approach by performing complex cryptographic computations off-chain to generate validity proofs. This results in higher base computational costs for the sequencer, which can translate to slightly higher fees for end-users in low-load scenarios—often 10-30% more than Optimistic counterparts. The trade-off is immediate finality: once a ZK proof is verified on-chain, the state is considered settled, eliminating withdrawal delays and enabling superior capital efficiency for DeFi protocols.
The key trade-off: If your priority is absolute lowest user transaction cost and your application (e.g., a social dApp, NFT platform, or low-frequency payment system) can design around the 7-day withdrawal delay, choose an Optimistic Rollup. If you prioritize instant finality and capital efficiency for financial applications like a DEX or lending protocol, where the value of locked capital outweighs marginal fee differences, choose a ZK Rollup.
ENQUIRY
Build the
future.
Our experts will offer a free quote and a 30min call to discuss your project.
NDA Protected
Confidentiality24h Response
Time to ValueDirectly to Engineering Team
No Sales Fluff10+
Protocols Shipped
$20M+
TVL Overall