Security clearance reform has been an action-item for the federal government for as long as personnel security programs have existed. The security clearance backlog has been a point of discussion for years, heightened by the OPM hack of 2015. Regular updates on processing delays come from the National Industrial Security Program Policy Advisory Committee, which meets regularly to recommend changes to industrial security policy.
Their most recent report walks through the current state of the security clearance process and how we got there. The report outlines five specific causes and effects related to the delays and backlog. From the report:
The report also outlines how stark the delays have become over the past two years.