wp_ob_end_flush_all slowing down website

Hello everyone,

wp_ob_end_flush_all can take from 25 to 60 seconds to run. It is causing a poor user experience. This happens to about 10% of requests. We use the W3 Total Cache plugin to help us speed up the site. I tried disabling object caching but it didn’t make a difference. Any suggestions for trouble shooting? I don’t see any errors related to this function in the logs.

Thanks in advance!