If you have a huge amount of mails to archive with your Content Collector instance you might experience a slow performance with the mail connector or even a crash due to a out of memory exception. This is because the default heap size of the mail connector is 900mb. To increase this you need to set the environment variable AFU_CHILD_JVM_XMX to at least 2000mb.
Keep in mind that Content Collector still is a 32bit application and you cannot use more than 2000mb JVM heap size. Restart you Content Collector server and you will see a dramatic performance growth.