I truly feel bad for guilds trying to learn new fights with this lag, embarking on new progression.
It's not just guilds doing progression. My guild has had HM EC on farm for months now and sometimes we can spend up to an hour wiping on Zorn & Toth because of the amount of lag people get during the rock-phase. We raid at 7:30-10:30 AEST (peak time) and from 7:30 to about 8:30 it is horrendous lag and then it gradually gets better as more and more people give up in EC. It is game breaking and needs to be fixed.
But BioWare will do what they do best - ignore the community and blame everyone but themselves.