With Bancor, users perform token conversions against smart contracts directly on the Ethereum blockchain. This requires computing transactions on the blockchain and registering the result in the public ledger, which incurs fees paid in gas to miners.
The gas price set by Bancor is the optimal price for a transaction to successfully execute on the Ethereum within 2-3 minutes. Bancor's gas calculation is based on an innovative estimation method that reduces the cost to users by excluding outsized gas prices from each block.
The calculated gas price is part of the transaction’s hard coded values. Thus, changing the gas price will cause the transaction to fail.
The smart contracts Bancor uses to enable on-chain liquidity are computationally intensive and can cause the cost of gas to be relatively higher than other services which simply swap tokens between buyers and sellers (yet usually charge added transaction fees and spreads).
As we look into the future, not only is Bancor continuing to optimize our network to reduce gas costs and provide the most efficient, low-cost on-chain conversions, but the underlying blockchains themselves (Ethereum and its current and future competitors) will mature to minimize fees over time.