Placeholders. (I'm explicitly focusing on my own reaction on this first point, because what I'm saying is very much a matter of personal taste.) I shudder at the idea of leaving placeholders in a manuscript. That impulse means that I've lost contact with the story and with the character. I'm no longer experiencing it. Instead, it's me as writer, from outside the story, trying to control it.
And when I come back later to fill in the placeholders, I always feel as if I'm more in authorial or editorial mode than in creative voice. I'm not sure whether that affects what I write, but it sure does affect how I feel when I'm writing.
Things go better when I dive right in and write the thing, rather than leaving a placeholder. If it doesn't work out, I can always come back to it later, once I see where the story is going.
The thing is, I'm almost always pleasantly surprised (either right then or later) by what I wrote. Often, without knowing it at the time, I put in some seemingly throwaway detail that turns out later to be significant. Or I write a line that jumps out at me and tells me what direction the story is going.
Practice. If you could more quickly get the words to the point where you are satisfied with them, you would spend less time fiddling with them. That was the reason I asked (in my comment) what triggers you to edit. If you notice patterns in the kinds of things that trigger you to fiddle rather than moving on, and if you could get better at those things, you would spend less time fiddling and more time writing the rest of the story.
So identify the most common triggers. Pick one trigger, identify what element of craft it is about, and practice it.
Do your scene openings not draw readers in? There are books and articles about that. Find a story that you loved, that pulled you in, and analyze how the writer did that. Then practice those things.
Do your scene endings not compel readers to turn the page? There are books and articles about that. Find a story that you couldn't put down, and analyze how the writer did that. Then practice those things.
Then pick another trigger. Study it. Analyze stories that do it well. Practice it.
With deliberate practice, you'll get better and faster at the things that are slowing you down.
Of course, your critical voice may simply raise the bar, but that's a whole other issue.
Critical Voice. Your critical voice loves you dearly. It wants nothing more than to keep you safe. It has an astounding capacity to imagine dangers. And it has an even more astounding capacity to focus your attention on every possible danger that it can imagine.
The problem is that our critical voice appears to have absolutely no capacity to distinguish between its imagined dangers and reality. It is afraid of everything. Deathly afraid.
So assess the dangers yourself. If you were to leave this bit of text alone (for now):
- What is worst thing that could happen?
- What is the best thing that could happen?
- What is most likely to happen?
You can ask these questions about anything your critical voice wants you to fear: What if I were to send this to an editor or agent? What if I were to publish it, with my name right there in huge letters on the cover?
Most of the time, I don't have to go beyond that first question. When I figure out the worst thing that could really happen, it comes nowhere near justifying the fear that my critical voice would have me feel.
Your critical voice loves you and wants to keep you safe. But it is afraid of daisies.