Do people with subconjunctival hemorrhage have a lot of pain?

Usually not. Subconjunctival hemorrhage is usually not painful at all. Some people experience an initial sharp pain that lasts for a few seconds, but aside from that, it should be painless. Persistent pain needs to be evaluated.
No pain. This is a spontaneous condition that always resolves in time (few days to weeks). It becomes more common with age, use of blood thinners including Aspirin and nsaids, straining (valsalva). It may or may not be associated with mild irritation, but pain is not associated with it. If you're having pain, you should see if it is something else.

Related Questions

Do lots of people get subconjunctival hemorrhage, or is it unusual?

Somewhat common. This is a benign bleeding from a small vein in the space under the clear conjunctiva over the white of the eye. Due to oxygen exposure it stays very red until absorbed. It can spread over a broad area and look very dramatic. Usually there are no symptoms except the redness. If the vision is changed, or there is pain, see your ophthalmologist. Otherwise you can wait it out. Read more...
Very common. Subconjunctival hemorrhage is very common from simply rubbing your eyes, allergies, etc. If recurrent or severe, you need to see your eye care professional for evaluation. Especially common in folks on anti-coagulant medicines... Read more...

What causes subconjunctival hemorrhage to last so long?

Slow absorption. This benign event in most cases, involves the absorption of blood from the subconjunctival space, which can do this but this is not the ordinary function of this space. So absorption takes a while but will happen. Read more...