Telegram limits the message thread on rates mentioned on FAQ
If you're sending bulk notifications to multiple users, the API will not allow more than 30 messages per second or so. Also note that your bot will not be able to send more than 20 messages per minute to the same group.
But it is not clear what is aggregation period for rates to calculate. E.g. would it be acceptable within two seconds to send |0|60| messages which would be still 30 mps?