Hi
Moving to VMware should not have a major impact on DB performance... if both hardware & VMware server are well configured.
With such an heavily used production environment some performance testing should be performed on the virtualized environment before migrating.
What Are the Best Oracle Database Load Testing Tools?
Impact of splitting DB & CI will depend on the usage you have of your CI.
Is it more a Primary AS (with user & batch activity) or a light weight CI (with only central services) ?
When the DB is moved away from CI host that instance will not connect anymore to the DB through IPC (shared memory) but through SQL*Net connection that is slower.
For this reason it can happens that some heavy batch are defined to run on the instance that is on the same host as the DB.
This could also have an impact on the update process that is running on the CI and could have an intensive DB activity, thus might impacted by switching from IPC to SQL*Net.
Best regards