i've personally spoken with the person whose wallet this belongs to, as i was concerned about a gpu miner; as well as the load it was placing on the server (no longer an issue). this person owns 400 machines each with twin x2630 cpus (4800 cores total). i was somewhat taken back, as few people have this sort of hardware 'laying around' at their disposal.

i went as far as to checking their share traffic, and to my relief they were all within standard distribution of cpu share size; just lots of them - there is never going to be a solution which prevents a person with this much processing horsepower. he was pretty upfront about it, so it doesnt bother me at all. there are a few members with ryzen cpus which achieve several kh due to the ryzen's 20mb l3 cache. one hundred of these machines could easily achieve 400kh.

the best part? 4800 cores and only 600kh? i think some people seriously need a reality check

regarding the possibility of a gpu miner? entirely possible.
any algorithm devised could have a gpu miner written for it; the actual part that matters is the efficiency, if the miner is only 25h/s faster than a cpu, is it even a concern?
you know there are publically available GPU miners for argon2? do you realise that they arent even twice as fast as a cpu?
they are opencl concepts written for that exact purpose, a concept. feel free to checkout arionum's gpu miner (https://bitbucket.org/guli13/arionum-gpu-miner); to find that it is not popular at all.

i've openly stated that i will attempt my own gpu miner; not in the quest for more speed, but to offset the load placed on the cpu (several members have mentioned their machines being too sluggish to use). i've also stated that once a working one is complete, it will be a public release for all.

i'm not going to remove any posts regarding gpu miner accusations; i've even screenshotted them for later embarrassment as i know the posters will likely retract later. thats crypto for you

james