Our Rails test suite runs in about 20 minutes (mostly integration tests) but parallelized on CircleCI with 3 workers it's down to ~6. If I run our entire suite locally on my 8-core macbook I get about 3 minutes but I can't do much with my laptop during that time because my system is monopolized, a colleague of mine runs it on a threadripper and it's sub-2 minutes. So running on Circle is well worth it, I can go top off my coffee, make a snack, answer emails, etc...