Performance on the email server has been very slow over the past month. There have also been various issues with backups on the mail server. The company has implemented several new systems and changes

Changing from RAID 5 to RAID 1 would likely maintain similar or slightly degrade write performance, and would not inherently cause widespread slowness or backup issues beyond typical performance characteristics.

A new monitoring server, if properly implemented, should have minimal impact on the performance of the monitored email server by simply collecting statistics, not causing significant slowdowns or backup failures.

A new antivirus program, especially on a busy server like an email server, can consume substantial CPU and disk I/O resources due to real-time scanning of files, emails, and processes. This heavy resource utilization directly leads to overall system slowdowns and can interfere with resource-intensive operations like backups, causing them to fail or perform poorly.

Changing from RAID 1 to RAID 0 would significantly improve disk performance by removing the mirroring overhead, directly contradicting the symptom of very slow performance.