If there are many contacts executing actions in your workflow at the same time, you may experience delays. This is what is called execution throttling.
If your workflow is experiencing execution throttling, you'll see the following message appear in your workflows tool:
In your HubSpot account, the workflows tool can execute actions for up to 20 contacts per second. To better demonstrate the impact of the execution throttling feature, let's look at an example:
- You have 6,000 contacts in your workflow scheduled to be sent an email at 10:30am
- 10:30am arrives, and your workflow begins executing the action of sending an email at a rate of 20 contacts per second. At that rate, the workflow will complete the action of sending email for the last of the 6,000 contacts 5 minutes later (6,000 / 20 / 60 = 5 minutes).
- If you had a second workflow that was also scheduled to execute an action (let's say it was to set a contact property value) for 3,000 contacts on the same day at 10:30am, that means 9,000 contacts were scheduled to execute actions at the same time. Across both workflows, the last of the 9,000 contacts would execute their action 7.5 minutes after they were originally scheduled. In date-based workflows, this can actually lead to contacts missing an action. Check out this article for a more in-depth explanation of this particular situation.
Your workflows' rate of execution is unaffected by other HubSpot users/accounts. Throttling is most common when you have enrolled a large list of contacts all at once into a standard workflow, as contacts will be scheduled to execute actions at very similar times.