Transaction Rate Limits and Optimizations

In this guide, you’ll learn about the transaction rate limits imposed by supported blockchains and Circle Wallets. You’ll also get client-side optimization tips to ensure smooth transaction processing within your applications.

Transaction Queue Limits

Blockchain Account Queue Limit

EVM-compatible blockchains typically use a Mempool system. The Mempool queues transactions sent from a wallet up to a certain limit defined by the full node. If you exceed this limit, you receive an error from the full node. All queued transactions in the Mempool can potentially be included in a single block. Therefore, you can estimate the theoretical transaction throughput as queueLimit / blockTime. However, various factors can influence whether your transaction gets included in a block, such as priority fees, network congestion, and network liveness. In contrast, the Solana blockchain does not use a Mempool system and, thus, does not have a queue limit. This contributes to its transaction throughput being significantly higher.

Account queue limit in different blockchains

Blockchain	EOA wallet	SCA wallet
Ethereum	32 transactions	1 transaction
Polygon	16 transactions	1 transaction
Avalanche	32 transactions	1 transaction
Solana (no Mempool)	Unlimited	Not supported by PW

Circle Wallets Transaction Queue Limit

The overall transaction throughput is fundamentally constrained by the blockchain account queue limit and the blockchain’s inherent throughput. To mitigate the impact of these limitations, Circle Wallets provide a queuing mechanism for transactions that exceed the blockchain limit for a certain duration. There is a limit on the number of transactions your wallet can queue in the Circle Wallets service to prevent resource wastage and false expectations. This limit affects the user experience when too many transaction requests are made. When you reach this limit, you receive an error message:

“Wait for pending transactions to be included on the blockchain before submitting new requests. EVM chains restrict the number of queued transactions per sender address.” (Error code 155264)

More detailed error descriptions and suggestions can be found in the Transaction error codes section.

To check the number of pending transactions and their status, use the listTransaction API endpoint. The transaction state should be one of the following: INITIATED, CLEARED, QUEUED, SENT.

Client-side Optimizations

While transaction queuing provides a convenient feature, fee fluctuations and network congestion can still impact transaction processing times. Below are some tips to ensure a smooth experience, especially when dealing with a high volume of transaction requests.

Higher Fees

Consider setting the fee_level parameter to at least MEDIUM or HIGH. This ensures that your transactions are processed with higher priority in a reasonable timeframe, reducing delays for subsequent transactions.

Managing Transactions

1. Monitor Transaction Status: Use the list transactions API to query the status of your transactions.
2. Cancellation and Acceleration: Use the cancellation and acceleration API to expedite transactions that have been pending for an extended period.
3. Transaction Notifications: Implement transaction notifications to confirm the completion of transactions before sending more requests.

Multiple Sender Wallets

Using multiple sender wallets can help bypass the per-wallet queue limit and increase the level of parallel processing. This strategy is generally effective across various blockchains.

Batch Transactions with Smart Contracts

Leveraging smart contracts for batch transactions can significantly reduce the number of transactions needed for repetitive tasks. For instance, instead of sending 1,000,000 transfer transactions individually, you can deploy an airdrop contract that processes transfers to 500 wallets in a single execution call, requiring only 2,000 transactions in total. Although a single contract execution call may incur higher gas costs than a simple transfer, it is often more gas and time-efficient for batch transactions.

For more details, please refer to our Airdrop template for Circle Contracts .

Summary

By understanding the transaction queue limits and exploiting the above optimization tips, you can improve the transaction throughput of your applications, thereby increasing their overall efficiency when interacting with blockchain networks.