The sending process of each message consists of 2 sub-processes:
The moment our servers receive your request to send a message, it is sent instantly. That means that the message is immediately sent to the next station/hop in the process (e.g. the local mobile network operator where the phone number is registered) and eventually to the phone itself.
In most cases the message is already received on the destination device before it is showing up in the message log.
We give priority to the sending part over the reporting part since that part is the time-critical one. Or in other words: The receiver of a message should not have to wait for the reporting part to happen until he can receive the message. And if it takes a minute for the message to show up in your log, that does not mean that the message was only received on the device a minute after sending.
The reporting part of the sending process consists of the writing of log entries and delivery status for each message and campaign.
Writing the log entry itself and updating its status can often take more time than sending the message and that is why it is designed to be an asynchronous process - meaning the one does not wait for the other.
Until delivery is confirmed (or not) by the destination, these messages will remain marked with the status SENT.
Sending & Delivery Speed
Taking the above into consideration, it is not possible to use the information log in order to measure sending/delivery speed. The only reliable method to measure the speed is to track the time between the send request and the actual reception on the device and requires access to the end device.