They don't have any special hardware, as pools don't meaningfully produce merkle roots in any volume. Since the original answer in 2013, mining has moved entirely to using the Stratum protocol which has the mining client generate their own merkle roots for proof of work, based on a template that is provided by the pool and is the same for all clients. Modern miners can be exhausting 10,000+ nonce ranges a second or more so the previous system is simply infeasible to use.

They don't have any special hardware, as pools don't meaningfully produce merkle roots in any volume. Since the original answer in 2013 which pertained to GetWork, mining has moved entirely to using the Stratum protocol which has the mining client generate their own merkle roots for proof of work, based on a template that is provided by the pool and is the same for all clients. Modern miners can be exhausting more than 10,000+ nonce ranges a second so the previous system is simply infeasible to use.