Paul says that the marrieds have to attend to their spouse (this takes time, the singles do not have this worry). He preferred singlehood so he can devote his life to ministry (implication is that if he was married he would not have as much time).
I think singles have a bit extra free time, perhaps not much depending on one's lifestyle. I do find that married people, especially those with kids, have less time for hobbies (even reading) or relaxing. I've gone through phases where I have more free time and sometimes less. Even though I am single and I do everything by myself, I find that I have a lot of spare time now especially weekends that are easy to waste away if I do not have anything planned. For me cooking is a hobby where I have time to try new recipes at any hour of the day even midnight and even fail a few times, but if I were married esp with kids due to time constraints etc, it would feel more like a duty to get dinner on the table quick instead of being a hobby. On cooking and shopping, I think it evens out between married and singles. For example, I can make a big pot of whatever and it can last me a week. With a spouse or especially with kids, that big pot will only will last at half that time and much less with kids (maybe only two days). Sure, the other spouse can share with cooking, but it is usually the wife who cooks a few days later. Spouses can share duties, but oftentimes one spouse helps the other spouse so together not much time is saved. For example, my friend's husband reviews and edits all of my friend's PhD papers, which is time-consuming and tedious, which he would not have to if he were single. She also ends up cooking or cleaning more because of him. So in the end, the shared duties isn't really adding spare hours to the married person's life.