Alas this is FUD - completely


Firstly, there is no "Stratum V1" it is simply just "Stratum"

The processing time to calculate the work is in microseconds or nanoseconds.
The Stratum data packet size to send full block work is smaller than any standard internet data transfer packet size.
The Stratum data packet size of full block work is typically less than 1400 bytes.

So the extra time would certainly be less than a millisecond and probably less than a microsecond.
So they are simply using FUD to make people think that it matters in Stratum, since that extra amount of time is effectively irrelevant.

HOWEVER, their pool specific changes to Stratum, will make this data packet MUCH larger.