Why is there a delay in returning the group info via getent on a group with a large number of members?

Issue

• When running a getent for a group with ca. 650 members it takes more than 2 seconds to get a result when sssd has no data in cache
• The ldap query only needs 0.15 seconds to return results
• Running a strace for the getent command shows that it waits on one system call
• This problem has surfaced after the enumerate option was set to false due to heavy network traffic