After update Sonata Switchboard I saw that application on browsers started to work very slow. There is a problem while users wants to pause and unpause. Sometimes system is pausing users by itself.
Did you update VitalPBX and Switchboard at the same time?
What version of VitalPBX and Switchboard are you using?
In same day but first Vital to version 2.3. 8-3 and after that switchboard to 2.1.1-2
You may try to restart the switchboard:
systemctl restart switchboard.service
Also, you may use the command "top" for determinate if there are any other process that is making your server slow.