Anothernoob

So give me a break here I am not savvy with boat motors, I just like to fish. So for my first boat I just recently got a 2006 tracker V16 laker. It has a 2014, 20hp mercury tiller motor with a 10P prop. I know 20hp isn’t much but I feel like it should be faster than the speed of smell. It’s very sluggish and doesn’t plane out very well, also it leaves a big wake behind it. It’s transom is about 20” and the cavitation plate sits about 2” below the bottom of the boat. Is it pretty much a general rule of thumb that it should sit even with the boat? Want to get some insight before I spend money on a jack plate that I may or may not need. Any info is greatly appreciated.