Re: 26.2; Strange slowness in some Info nodes

[<Joe_Trivers@amat.com>]

> > Crystal ball says it's related to the fonts you use.  Does setting
> > inhibit-compacting-font-caches to a non-nil value help?
>
> Yes, thank you. With that set to t the scrolling slowness disappears.
>
> The strange thing is I tested the problem with emacs -q, so it
> didn't use any of my usual fonts, it picked up only the windows
> system default fonts.
>
> I checked the affected info nodes and I don't see any special
> formatting or fonts there compared to other info pages which were
> quick to scroll.
>
> The only apparent thing is the symbol names. Those use the
> Info-quoted face and curly quotes :
>
>   Compare ‘make-list’ with ‘make-string’ ..
>
> Maybe those cause the slowdown.

I get the same thing.
What's more, it seems to depend on the location in the file being displayed.
That info file is quite large, almost 4MB, and the "Building Lists" node is at line 6307.
Paging up and down after C-x n w (widen) still takes a lot of time, depending on the exact location in the file.
Moving to the middle of the file (M-g M-g 45000) and paging down is effectively instantaneous.
Repeatedly paging back up is also instantaneous, until I get to the page at line 44953, which takes half a second or more. The location in the file seems to be consistent.
That page contains a '⇒' character, as do essentially all the pages in the "Building Lists" section. Setting inhibit-compacting-font-caches to t fixes it for me, too. So I guess it's unrelated to file size. How about that.
I'm on GNU Emacs 26.1 (build 1, x86_64-w64-mingw32) of 2018-05-30.
/Joe
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