Is there a way to see bottlenecks in the review process?

If you believe there is a step or Form in your workflow that is taking more time to complete than expected and therefore holding up or slowing down other reviewers at different stages of the review, you can check some time to completion statistics in Datarama. 

In Datarama, select your Level or Form of interest in the Data to Display section in the Report Settings tab. Then, in the Advanced Options tab, select the "Show time it took reviewer to complete" option from the checklist. Click Run Report. 

Your report will contain a column with a shortened version of each Form's name, and the time it took each reviewer to complete the Form in seconds. If you notice a specific Form is taking significantly longer to complete than others, it may need some clarification or modification.