There probably are a lot of parents here wounding just that and not too many parents hear to answer you as their kids arnt in school yet.
There are a couple of other threads on this topic but I can share my experiences.
Yes my kids do get bored at school. But to be fair many kids are bored in school. Not just because they know the answers but often because they havnt a clue! Or purly because the lesson is boring. I find it a constant effort to get them extended during class lessons. I need to be quite visable and present to ensure they get an education that caters to them. Some years we have no love and other years they get very understanding teachers.
Most classes these days have a couple of very bright kids in them so it is likely your child won't be the only one reading on entry to school. It is likely they will be reading at a higher level though. My oldest was one of 4 early readers and my second child was one of 3. To be honest they have all been ahead of their peers in math but this just allows them to zip through their work faster and move onto something else. It's the "something else" that you need to be on top of. Some years it is just colouring in! On good years it is more advanced work including critical thinking, puzzles, mazes or free time to read.
Overall my children LOVE school. They love finding most everything easy, they enjoy always having some piece of information to contribute, they get a kick out of doing school projects that send their teacher off to do research to see if they are right.
I also wouldn't stop doing early learning just to avoid the issues. The issues are so minor in the bigger sceme of life. I did however move the focus of what I teach them. We teach depth and mastery in our after schooling and I spent much more effort on encyclopedic knowledge than I did on early reading. This was my choice based on knowing what school they would be attending and the schools philosophy on teaching ( not a huge amount of choice around here within the family budget) perhaps if I had a more flexible schooling option I would change the focus for EL and teach more solid reading earlier.
I see NO PROBLEM with teaching times tables, digraphs, periodic tables, poetry.....early. Whether you teach it or not you will always find parents and friends who disagree with your parenting choices. Frget about them and decide what YOU value most in education.