Importance of GRE for computer science PhD applicant I am currently a prospective computer science Ph.D. applicant with a 3.75/4.00 GPA at an R1 CS school ranked in the top 30. I am considering applying to 15 schools roughly in the top 50. I have an extremely strong research background with one first author ML pub in a reputable IEEE conference and a second author applied ML/psychology journal article under review. My letters of rec will all likely be very strong and from well-known professors that I have worked under or with for at least 6 months. That said, I have a few questions about the application process:

I am not the best standardized test taker, and I currently am looking at quantitative GRE scores of around 75th-80th percentile with verbal scores in the same range. Will my subpar GRE scores likely prevent the comparatively stronger portion of my application from being reviewed at many schools? With this in mind, should I retake the GRE until I'm closer to the averages of the schools?
I am going to complete my undergraduate in 2.5 years and am hoping to enter a Ph.D. program directly after graduation. Will the reduced length of my undergraduate career reduce my chances of acceptance, or is this viewed somewhat favorably?

Any insight would be greatly appreciated. Thank you.
Admissions committee in strong CS PhD programs are primarily looking for concrete evidence of research potential.  Neither GRE scores nor the ability to take lots of undergraduate classes provide that compelling evidence.  Fortunately for you, a first-author CVPR paper and strong recommendation letters would!
Given your research record and the likely strength of your recommendation letters, no admissions committee is going to care about your GRE scores (even if the ongoing pandemic allows you to take the GRE in the first place).  At least in the top 10-20 CS PhD programs, GRE scores only matter if they are really bad, or if your case is otherwise truly borderline.  My department hasn't required GRE scores for graduate applicants for over a decade.
Similarly, I don't think finishing early will have much effect on your chances.  A few people will be impressed, a few people will be concerned about possible burnout, but most people won't care, especially given your research record and the likely strength of your recommendation letters.  Unless you have financial reasons to finish early, you might be better off in the long run staying where you are and expanding your research portfolio.  (If you eventually apply for academic jobs, hiring committees won't care how quickly you finish your PhD; they'll care primarily about the strength of your research record.)
This is a great issue to discuss with your letter-writers.  See also Mor Harchol-Balter's detailed advice for CS PhD applicants, based on her experience at Berkeley, MIT, and CMU.  (Her description also matches my experience at Illinois, and other departments like Washington explicitly recommend her advice.)