1a. I think cats are cute and move quickly. -- (i) You think cats are cute; (ii) You think cats move quickly. To me, it seems slightly odd to say that you think cats move quickly.
1b. I think cats are cute and they move quickly. -- Could mean the same as 1a, or, probably more likely, could mean: (i) You think cats are cute; (ii) Cats move quickly. Combining the two ideas wi