Some classes were boring, sure, I slept through them. But for the most that was not the case and the load never seemed to be excessive. (studying in eastern, then western europe)
Severely underpaid teachers and a focus on testing leads to formulaic memorization of (what a lot of us thought) was drivel, just things to know and forget after the test. High school for me started very early (about 6:45/7 to catch the bus), so it was miserable. I did have some classes that were the exception, but for me all school did was try and beat the drive to learn out of me. In middle school I got punished for reading ahead in our assigned literature. We also had to deal with a powertripping principal for years.
And that's to say nothing of the completely whitewashed US "history" we learned.
I actually was homeschooled for a few years, so I have experience with both systems. The issues I had with homeschooling were the overly religious program my parents used, and the lack of socialization.
I will never put my kid in a public or private school system, provided that I find a community for us to engage socially in, that we find a good curriculum that's not religious, and that either myself or my partner engages in it full-time.