I am on the kovan network and use web3 to execute transactions and query the blockchain. If I send many requests in short time intervals (1-10 seconds) one after the other, I get several empty objects as reponse which look like this:

{
  "address": "",
  "blockHash": "",
  "blockNumber": 0,
  "logIndex": 0,
  "transactionHash": "",
  "transactionIndex": 0,
  "transactionLogIndex": "",
  "type": "",
  "id": "",
  "returnValues": {
    "0": "",
    "1": "",
    "orderId": "",
    "amount": ""
  },
  "event": "",
  "signature": "",
  "raw": {
    "data": "",
    "topics": null
  }
}

Is this a problem of the kovan network or something else? What is the best way to improve this?

I am on the kovan network and use web3 to execute transactions and query the blockchain. If I send many requests in short time intervals (1-15 seconds) one after the other, I get several errors >70% of my transactions fail! Here is the error I get:

Error: Returned error: Transaction gas price is too low. There is another transaction with same nonce in the queue. Try increasing the gas price or incrementing the nonce.

Error: Returned error: Transaction nonce is too low. Try incrementing the nonce.

If I send a transaction every 20 seconds, every transaction works! Is this a problem of the kovan network or something else? What is the best way to improve this?