According to my understanding, having many workflows in a jira system decreases the performance.
Confluence page -
https://confluence.atlassian.com/display/ENTERPRISE/Scaling+JIRA also states that as number of workflows increases in a system, response times to create and edit an issue also increases.
However, when a jira project is created either by using a template or through an agile board, a new default workflow gets created as well.
Therefore, over a period of time a jira system will have a lot of default workflows.
Can you please let us know whether default "Agile Simplified Workflow" has any affect on jira's performance or only customized workflows affect the performance.