After a first round of revision, I have a paper whose status on Elsevier is "Accept, after minor Revision". Indeed, referees pointed out some revisions (very minor ones) which are relatively easy to be fulfilled. I made the necessary modifications in one day. My question, is really a bad signal to resubmit very quickly a paper? What can be pros and cons of that?
As long as you don't exceed the deadline, I don't think it really matters - it won't get "more accepted" for being resubmitted quickly. Of course, sometimes it can help getting it into production faster.
However, if you have spare time I'd suggest not rushing the resubmission. While you could get away with taking a day, consider taking closer to a week. Forget about the paper for a couple of days, and carefully proofread it again - both the revisions, and the unchanged parts.
A one day turnaround is not unreasonable for minor revisions. Think about how documents are processed in the work world.
Also, note that minor revisions may even mean the paper does not go back to the reviewers but the editor just looks at it and signs off on it. He sees that you have made the changes. Also, good if your cover letter is clear for him. "I have implemented all changes except number 5 of reviewer 2, which is no longer relevant based on other changes". Or whatever the story is.