This problem can present itself in two different ways:
This problem has been identified as software defect RR-107612.
The post-processing step is slow for Linux VMs as each write operation requires a mount of the VMDK. Linux-specific steps on post-processing exported volumes take about half the time of all the post-processing phase.
Note: This issue does not happen with the export jobs for Windows VMs because the post processing process is different.
A patch has been created to change the logic of the application allowing it to batch all the post-processing writes into a single mount, which improves the efficiency for this specific task.
Please contact support for assistance applying this patch.