What is throttling?

Throttling is a security mechanism that keeps a server healthy and responsive. It is called "throttling" because it limits the workload coming through the server by regulating network traffic and minimizing bandwidth congestion.

Microsoft uses throttling as a way to manage the operation of Office 365 and to ensure that all customers receive good service. To this end, Microsoft offers only a limited amount of bandwidth to each of their Office 365 or OneDrive customers and any applications installed by these customers cannot exceed the allocated amount.

If limits are exceeded, it can impact performance speeds in the Keepit app and in turn can be one of the reasons why you may encounter slow backup and restore speeds.

Can I do anything about it?

All Microsoft Office 365 applications must deal with throttling and little can be done to change this through configuration or regular troubleshooting.

If you experience slow performance in Keepit, please ensure that you are not running other data intensive solutions against your Microsoft Office 365 tenant, such as synchronization or secondary backup services. 

If this is not the case, then you can have Microsoft temporarily raise your throttling limits on Exchange.

The Office 365 support team can request to have the following limits raised:
EwsMaxBurst : Unlimited
EwsRechargeRate : Unlimited
EwsCutoffBalance : Unlimited
(And highest limits available for EWSMaxConcurrency)

This is a standard procedure, and you can contact Microsoft support to get it changed. Typically for 90 days. These changes affect only Exchange, not SharePoint, OneDrive, or Groups & Teams.