Based on the provided process variants, we can identify several root causes for performance issues in the process:

1. Rejection loops:
	* Variants with loops leading to resubmissions after rejections by ADMINISTRATION, SUPERVISOR, or PRE_APPROVER generally have higher performance times. For example, in the variant:
	```
	Declaration SUBMITTED by EMPLOYEE -> Declaration REJECTED by ADMINISTRATION -> Declaration REJECTED by EMPLOYEE -> Declaration SUBMITTED by EMPLOYEE -> Declaration APPROVED by ADMINISTRATION -> Declaration APPROVED by BUDGET OWNER -> Declaration FINAL_APPROVED by SUPERVISOR -> Request Payment -> Payment Handled
	```
	The process takes almost twice as long (performance = 2061236.516) compared to a direct approval process (performance = 1084338.407).2. Multi-level approvals:
	* Variants with multiple approval steps tend to take longer. For example, the variant with PRE_APPROVER and SUPERVISOR approval:
	```
	Declaration SUBMITTED by EMPLOYEE -> Declaration APPROVED by PRE_APPROVER -> Declaration FINAL_APPROVED by SUPERVISOR -> Request Payment -> Payment Handled
	```
	has a higher performance time (861058.409) compared to a variant with only SUPERVISOR approval (854633.975).3. Missing data handling:
	* Variants with the "Declaration REJECTED by MISSING" step show potential data handling issues, leading to resubmissions and increased performance times. For example:
	```
	Declaration SUBMITTED by EMPLOYEE -> Declaration FINAL_APPROVED by SUPERVISOR -> Declaration REJECTED by MISSING -> Declaration SUBMITTED by EMPLOYEE -> Declaration FINAL_APPROVED by SUPERVISOR -> Request Payment -> Payment Handled
	```
	has a high performance time (1947246.400).4. Rejection and resubmission handling:
	* The variant in which the declaration is rejected by ADMINISTRATION multiple times before final approval and payment handling takes much longer (performance = 3502608.250) than other variants. This could indicate issues with communication or data accuracy during the initial submission.

Addressing these root causes could help improve the process performance by reducing the number of resubmissions and rejections, optimizing the approval process, and ensuring data accuracy and completeness at each stage.