Exactly. I used to get cover letters all the time that said something like "I know the book starts kind of slow, but don't worry, it gets really good around Chapter Five!"
In which case you may need to rethink things a bit before you submit it to an editor.
As I've mentioned here before, I've been to two David Gerrold writers' workshops and at one of them he talked about wannabe writers who have a dog-eared manuscript stuck in the back of a drawer, one that had done the rounds and was never getting anywhere.
He suggested pulling it out, tearing off Chapter One (yes, with that opening line you laboured over for months and months), and tossing that bit away. Or, for a short story, tearing off page one. Too often people waste the audience's time getting to the first interesting bit, and by then a manuscript reader would have consigned it to the round file.
I went home and tried that with a university essay I'd been wrangling with, and ended up being the only person in my group to get a Distinction. I was congratulated by the markers for not waffling around at the beginning, like everyone else had! Best David Gerrold advice ever! A few months later, I'd also been commissioned for my first piece of professional writing, based (I found out much later) on the recommendation of two lecturers who'd read my essay.