IOPS capped on a VM within Hyper-V

quick question ... we get 100,000 IOPS once we used SQLIO against a VHDX file . ( let's say disk2.vhdx) 

from inside a VM , we mount the same disk as a secondary disk and run SQLIO against it ; we get about 30,000 IOPS. 

There is no QoS for storage defined yet .. 

Is there any other limit ? we increased VM memory to 64 GB , processor to 8 and never went above 30,000