At what point in a book do you decide to close it and put it down for good?

I am having issues with this question right now. I don’t know at what point I should stop trudging through a book.

Here’s the scenario. I’m reading By Gaslight, which I was so excited to read when it first came out. I will admit, mostly because of the cover. But the premise sounded fantastic as well. It’s set in Victorian London and I’m a sucker for some good historical fiction.

There are a couple of things that bother me.

1. The pacing is slow AF. By Gaslight taps out at 600 pages and it could easily be half that while still retaining 90% of the story, in my opinion. I think it’s so long because there’s two narrators (so far) and there’s a lot of flashbacks.
2. THERE ARE NO QUOTATION MARKS. Why is this a style?? I find it hard to figure out who is talking sometimes. I especially find it hard to figure out which portions are talking portions and which are internal monologue portions since both can be in one sentence. It may not seem like a huge problem, but it irks me. And it means I have to reread some passages.
3. There are a ton of run on sentences. While this is probably lends itself to the style of Victorian London, the content editor in me is silently screaming.
4. I’m no longer super invested in what is happening.

Despite all of the above, a part of me is still curious as to where it goes. I may not be invested in the characters, but I still find myself wondering what happens next. I’m standing alongside Pinkerton or Foole and experiencing things as they are; finding out pieces of the puzzle as they do. It’s a slow burn, but I don’t know if it’ll be a good pay off at the end.

Is this just me being very impatient? Should I wait it out? I have no idea.

Let me know how you decide to DNF things!

-M