Check out this video showcasing the work done by a Vizioncore engineer.  With something called the vzboost-vmkmod module written by the Vizioncore software engineer, vRanger and other Vizioncore products are able to break the VI3 COS write limitations and greatly speed things up.  I'm not 100% sure what was exactly changed or modified in the original kernel, but this video clearly shows a boost in write performance. 

If you have any more info on this, please share it with us.

In this video, you'll see the original VMFS drivers getting around 280 writes per second, and then after the vzboost driver is loaded, the speeds jump to

Ever wondered why vRanger is copying VMDK files via the COS so fast ? Here’s the answer. Someone from Vizioncore showed me this video at the TSX in Nice. The vzboost-vmkmod module is written by a Vizioncore software engineer who studied the original VMFS module code from VMware and rewrote it into the vzboost-vmkmod module. You can take a look at vzboost in action using this link. First you see the original VMware driver running with 280 writes per second after the vzboost driver is loaded the speeds will jump to 641 writes per second.

Thanks to Eric Sloof for finding and sharing this!