ethers.js: Contract methods are slow

Summary

Contract methods that send transactions are approx 5x slower than they could be. The reason seems to be poll function used in sendTransaction method of JsonRpcProvider, with a hardcoded interval.

This is a crucial factor of the speed of test execution, written in ethers.js.

Important notes

• I am using JsonRpcProvider
• I am connecting to devnet (geth modified by 0x team for testing purposes)
• Full code to reproduce example is available here.

Steps to reproduce

I prepared a simple test comparing the speed of test execution of truffle vs ethers, here is a snippet:

  ...
  it("truffle", async () => {
    ...

    console.time("    truffle send");
    await metaCoinInstance.sendCoin(
      safeMathInstance.address,
      accountTwo,
      amount,
      { from: accountOne }
    );
    console.timeEnd("    truffle send");

    console.time("    truffle call");
    await metaCoinInstance.balances(accountTwo);
    console.timeEnd("    truffle call");
  });


  it('ethers', async () => {
    ...
    console.time("    ethers send");
    await coinContract.sendCoin(mathContract.address, accountTwo, amount);
    console.timeEnd("    ethers send");

    console.time("    ethers call");
    (await coinContract.balances(accountTwo));
    console.timeEnd("    ethers call");
  });

Common results are sth like this:

  Contract: MetaCoin with truffle
    truffle send: 50.286ms
    truffle call: 40.342ms
    ✓ should send coin correctly (104ms)

  MetaCoin with ethers.js
    ethers send: 138.884ms
    ethers call: 13.162ms
    ✓ ethers (406ms)

Results vary a lot from run to run, but the general pattern is:

• Calls 1.5-3x faster for ethers.js
• Sends are 3-5x slower for ethers.js

Potential cause

My guess is the reason poll methods used in JsonRpcProvider here.

It seems to use options.onceBlock, that does not work well for subsecond block intervals here.

Proposed solution

Add option for faster polling for tests.