Speed of the campaigns varies based on the amount of channels you have available in the panel. And also, the settings that you want to configure the channels to run the campaigns.
Speed of text, image, video and PDF campaigns vary due to file size while running campaigns also. Since, large files take time to upload on WhatsApp server and hence, require more time to finish campaigns.
On average, you will be able to send anywhere from 50,000 to 1,00,000 messages per hour depend on the settings config in the backend and also depending on the amount channels added into the panel.
We can also configure the server to higher configuration incase you require more faster speed for sending, just that you need to have ample amount of WhatsApp channels stored in the system to handle larger volumes.