Which steps in the value stream should be the main focus when prioritizing improvement items?

According to the SAFe DevOps Practitioner 6.0 study guide1, when prioritizing improvement items, the steps with short Active Time and high %C&A in the future-state map should be the main focus. Active Time is the amount of time a step spends on performing work, while %C&A is the percentage of capacity utilization of a step. The future-state map shows how the Value Stream will look like after implementing improvements, based on customer feedback and business value. The improvement items are ranked by their impact on flow efficiency, customer satisfaction, and business agility. The steps with short Active Time and high %C&A in the future-state map indicate that they are bottlenecks or waste sources that need to be eliminated or reduced as soon as possible. Therefore, they should be prioritized for improvement actions.