GasBoost: How TUSD uses 15+% less gas than every other Stablecoin
The GasBoost technology was developed at TrustToken by William Morriss with support from Terry Li
GasBoost makes TrueUSD the lowest gas-cost stablecoin on Ethereum today, saving transaction costs for traders, dapps, and exchanges. Though we don’t have comprehensive proof, we are confident that TrueCurrencies are also the cheapest ERC20 tokens on the entire Ethereum blockchain.
GasBoost is always running, decreasing the cost of every TUSD transaction. You do not have to do anything to use it, and it is available for the entire suite of TrueCurrencies on Ethereum.
What does it mean to reduce gas costs?
TrueUSD is an ERC20 token running on Ethereum. The Ethereum network charges a transaction fee, the product of gas price and gas consumed. GasBoost reduces the gas consumed by ERC20 transfer and transferFrom, both used to move tokens between accounts. The gas price, however, fluctuates throughout the day, depending on the usage of the network. Gas can be expensive, especially during peak trade times or during a phenomenon like Cryptokitties.
How does it work?
Ethereum issues gas rebates for transactions that free up storage or destroy smart contracts. When you transfer TrueUSD, the smart contract detects how much gas you use, and refunds up to half of the gas consumed by freeing storage or destroying smart contracts.
Storage and contracts are purchased at lower gas prices when Ethereum has spare bandwidth, arbitraging gas price volatility. For example, the contract destroyed in the transaction screenshotted above was created at 0.26931421 gwei and destroyed at 22 gwei, saving $0.090 while costing $0.004, a net gain of 2150%.
What methodology did you use to estimate the gas cost of each stablecoin?
For each stablecoin, we averaged the gas cost of these four cases²:
- A transfer that reduces a wallet into an empty wallet
- A transfer that empties a wallet into an empty wallet
- A transfer that reduces a wallet into an existing wallet
- A transfer that empties a wallet into an existing wallet
Each stablecoin consumes different amounts of gas for each of these four cases because the SSTORE operation cost depends on the zero-ness of the storage changed.
We see the biggest differential (31%) in fees in cases where a new holder is being created on-chain. You benefit from this savings in cases where you send TUSD (vs. other stablecoins) to an exchange. Exchanges also see these savings when users withdraw TUSD. This builds on top of other features like AutoSweep that we have built to reduce fees that exchanges and OTC desks pay when using TUSD.
You can view the extended breakdown here.
Why This Matters
If your DApp does many $1–10 transactions, then a $0.10 transaction fee represents 1–10% of your total transfer. We believe that the majority of cryptocurrency usage will begin to move beyond trading on exchanges into more daily applicable uses like remittances, p2p payments, microloans, and even micropayments.
For these non-speculative transactions, consumers will shop around for the best rates in the same way that someone remitting money from the U.S. to the Philippines will compare rates between Western Union and Moneygram.
We welcome any feedback you have on this article and please reach out if you are interested in using TUSD in your application.
References
¹The Ethereum Yellow Paper details the costs and rebates of every opcode.
²To double-check these numbers, you can run “eth_estimateGas” from the largest holder account for each of the four cases, defaulting to 1 unit for reduction. In the empty into new and empty into existing cases, subtract 15000 gas used to account for the intrinsic refund. For GasBoost, you have to subtract more based on how much is being refunded. The recipient should not have any zero bytes in their address, otherwise, the measured gas will be too low by a multiple of 64. Profiling code available upon request.
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GasToken.io pioneered gas tokenization in 2018. Our refund techniques are similar to theirs, but we do not CALL into a shared gas pool. Instead, our gas is locally available in our smart contracts, which reduces activation overhead.
Here is the GasBoost code deployed in the TrueUSD smart contract.
