Which makes it a bit mysterious why they'd slow down right there if they maintained higher speed otherwise. Such a speed change should have defeated the entire purpose of the comet-tail-fly-through maneuver.
Voyager seemed to move by making a series of warp speed runs, followed by periods of sublight speed, then returning to warp. The Romulan ship might have been doing the same time, exacerbated by the cloaking device the warp drive could only be run for a few hours at a time. The ship would then have to slow to sublight periodically to recharge or cool down. Then it returned to warp.
When the Commander slowed to sublight, the Enterprise would too.
The Romulan Commander timed one of these cool down cycle to coincide with the comet's position, passing through a comet's tail to attack a pursuer being an old favored tactic of the Commander.
The only problem with that is that it then asks the question how did the Romulan ship manage to move so quickly along the Neutral Zone without a FTL drive? It also attacked and destroyed three Earth outposts in fairly quick order that had be located a good distance from one another...
The Romulans destroyed outposts 2,3 and 8, and then outpost 4. But not outposts 1, 5, 6 and 7. I wonder if there was more than one Romulan ship? Maybe each destroyed outpost had a single ship assigned to it's destruction. A fast out and back mission. As opposed to one ship zig zagging up and down the line of outposts, hitting some, skipping by others.
