why ethereum pools don't use vardiff ?

[peoples]

Hey,

wondering why all big ethereum pools don't use vardiff ?
I stumbled accross sammy007 comment here: https://github.com/sammy007/open-ethereum-pool/issues/10

Can someone explain me why vardiff on ethereum is a security issue ?

Thanks
regards

[nc50lc]

I saw this posted to ethereum's forum 5days ago and sadly didn't received an answer

Just a guess: Due to the nature of Ethereum's miners which mainly consist of GPU rigs, the hashrate per rig or worker wouldn't be as diverse as other coins that can be mined using processors, GPUs to ASICs.
With that, variable difficulty isn't necessary if the pool is expecting a small range of hashrates from the miners.
They can just open two or more servers to choose from than enabling Vardiff.

I'm seeing some ETH pools that has Vardiff though.

[peoples]

could be yes.
But from a pool operator point of view it sill makes sense to run vardiff. Simply to lower or even out server / network load.
With my knowledge so far i don't see any security issue with vardiff on ethereum.  But the big pools out there like ethermine / nanopool and dwarfpool don't use vardiff. So i'm curious to know if there is a reason behind it.

[GhostWithin]

I never knew that vardiff could have security problems.
The only thing I know is that fast and slow miners cannot be mixed in the same worker.
In this case, there may be problems, but they arent related to safety