Tested again. No totems and I'm not spec'd for lightning overload.
I kept casting until 1000 mana
1) /cast lightning bolt 262,142 damage, 1948.3 dps
2) /castsequence lightning bolt, lightning bolt,lightning bolt,lightning bolt,lightning bolt,lightning bolt,lightning bolt,lightning bolt,lightning bolt 291,531 damage, 1675.1 dps
I only had 125ms lag. When I tested it before I had 233ms lag (horde were in IF and I didn't know it). It seems like the better your latency, the less delay. So make sure to add that to your tests.
Naked test (only tabard, no totems):
1) /cast 18,238 damage, 459.3 dps
2) /castsequence 16,314 damage, 372.0dps