Poor performance with ESXi replication.
Current assigned resources on the virtual appliance are not sufficient for replication of some larger VM's.
1. Upgrade the Hardware version. This is done by powering off VM, and once the VM is powered off in the right click menu, choose upgrade hw version which will be 7 for ESXi 4 and 4.1. ESXi5 hw version is 8.
2. Add another CPU to a total of 2
3. Add at least 2 gig of Ram.
4. Ensure Vmware tools are the most current for the Vmware version.
5. Add a NIC with the type other then Flexible. E1000, or VMXnic will perform much better for you. Remove the original NIC type.
Reboot the Virtual Appliance, and start a replication.