Bad performance/higher cpu usage after changing from UBI 8 to 9

Hey folks,

we running OCP 4.15 on-premise in a vsphere-cluster. We are running an self developed php-fpm application on UBI. After upgrading the baseimage from UBI 8 to 9 without any other changes, we lost 50% performance, so we need two times cpu to get the same performance.
When we run the UBI 9 container on a podman linux host, the performance impact isnt there.
Have you any idea what the reason could be?
Thank you.

Kind regards,
Sascha