I've been thinking about this for awhile now and how much in awe I am at the martyrs that sacrificed themselves either by crucifixtion or some form of execution. I wish I had that deep of a spiritual conviction to do the same if the time ever arises. I can't even imagine the agony one must have had to endure.
I wanted to ask a prayer request for those that suffered in the flesh and those that may suffer in the flesh in the future that I hope God is with them and doesn't abandon them when the despair is too much to carry.
Lord have mercy.
My limited understanding of Christians who have encountered such trials is that those who have acquired the Holy Spirit fully in the sense of Saint Seraphim of Sarovhttp://www.fatheralexander.org/booklets/english/sermon_st_seraphim.htm
are protected from pain and are immersed in bliss throughout their trials.
e.g Saint Lawrence who was roated alive supposedly said "Turn me over. I am done on this side."http://en.wikipedia.org/wiki/Lawrence_of_Rome
Another inspiring account is of the burning of Saint Polycarp who was unharmed by the firehttp://www.catholic-forum.com/saints/golden332.htm
As for Christians who were not so full of the Spirit, I would not like to speculate as to whether they suffered greatly or not.