Recently we've made improvements to out stratum servers. This should improve the stability of large SHA256 & SCRYPT ASCI miners. We've reduced the number of work restarts by excluding AUXPOW coins from issuing new work requests. This should show the biggest improvements on the algos which have a lot of AUXPOW coins such as SHA256 and SCRYPT but will see improvements on any algo with AUXPOW coins enabled.  Inadvertently, this should also have a slight improvement to NiceHash miners as NH charges extra fee's for work restarts.

Cheers!