Can you give me tips on how I can expedite the process? My professors compliment me on my work, but it’s not much of a consolation considering it takes me 10 times longer to complete their assignments than it should. It’s not that I’m a perfectionist or particularly distraction-prone - I just seem to be incapable of coming up with something coherent within the time span of 30 minutes to an hour. Am I just stupid?
4-8 hours? periods? days? weeks?
fixed.
“It can take me 4-8 hours to complete simple, one-page writing assignments.”
Welcome to college.
You sound like you are really considering the topic carefully, and satisfying your profs. I wouldn’t give that quality up in your work! One thing you might try is reading the topic right before you go exercise, walk somewhere, or shower. Mull over the topic while doing something else you probably need to do anyway. Maybe when you sit down to write you will be able to produce something more quickly.
Go to your professors office hours. Tell them what you told us and see if they have advice.
Go to your college’s Writing center and ask them.
REad this book: “How To Become a Straight-A Student The Unconventional Strategies Real College Students Use to Score High While Studying Less” by Cal Newport to learn how to become more efficient.
The only thing that ever worked (or works) for me is to just start writing. Good writers write. The more you write the faster it gets. You may be struggling with paralysis by analysis. This is an evil demon in my life. 
My son (he does the same thing) and I have talked about this many times.
Perfection is the enemy of completion.
Write, edit, write some more, edit some more. Let it go. Give yourself a reasonable time limit and then walk away.
Writing is like any other skill: it takes practice. The more college writing you do, the better you’ll be at it. In the meantime, accept that the level of work you find acceptable (and your professors compliment you on) simply takes time. So start as soon as you get your assignment to avoid stressful overnights, etc. to meet your deadline. And cheer up. Many students have difficulty writing “a coherent one-page assignment.” You’re certainly not alone.
Look at the syllabus and find out what percentage of your grade each assignment is. Set a time limit based on the assignment’s worth - limit yourself to (for example ) one hour or less for a low stakes assignment.
OP, I am going to suggest you go to the counseling center. Listen to me: you are clearly NOT stupid. But I think you are struggling with college level work and self-esteem issues. I saw your other post too. Stop beating yourself up. You are in college! That is fantastic! Don’t let the first few weeks dictate the rest of your college experience.
And that’s when you major in engineering and take as few writing courses as possible.
I got all A’s in my writing classes because I had some of the best papers but yeah, a 2 pager is an all-nighter.