Adding to what 'vbrowncoat' had already mentioned. I had come across this issue and the possible solutions were the following:
1. Enable network compression in replication wizard for this VM.
2. If issue persists, disable guest unmap within this VM. For instructions, you can refer this KB --> https://kb.vmware.com/s/article/2150251
Step.2 resolved this issue on most of the instances I had come across.