I have taken 1 course in summer before, Math 2ZZ3, and it was a lot easier than in regular year.

They're not supposed to be easier than Fall/Winter courses but the fact that you're doing fewer courses/extracurriculars in the summer and the courses are a bit more condensed tends to make them feel easier (though there are some times where there are changes to summer courses that end up making them easier/harder as well).

I also found since the course was more condensed, I remembered the material easier.

i was barely passing a course in which i dropped during the winter, took it in the summer and received an 11. if you get a reasonable prof it should be easier but only if you put in a half decent effort