// ✅ Good: parallel requests
const [block, balance, nonce] = await Promise.all([
  provider.eth_blockNumber(),
  provider.eth_getBalance(address, 'latest'),
  provider.eth_getTransactionCount(address, 'latest')
]);

// ❌ Bad: sequential requests
const block = await provider.eth_blockNumber();
const balance = await provider.eth_getBalance(address, 'latest');
const nonce = await provider.eth_getTransactionCount(address, 'latest');

const cache = new Map<string, any>();

async function getCachedCode(
  provider: Provider,
  address: Address.AddressType,
  blockTag: BlockTag
): Promise<Response<Hex>> {
  // Only cache historical blocks (immutable)
  if (blockTag !== 'latest' && blockTag !== 'pending') {
    const key = `code:${Address.toHex(address)}:${blockTag}`;

    if (cache.has(key)) {
      return { result: cache.get(key) };
    }

    const response = await provider.eth_getCode(address, blockTag);

    if (!response.error) {
      cache.set(key, response.result);
    }

    return response;
  }

  // Don't cache latest/pending
  return provider.eth_getCode(address, blockTag);
}