Issue 1:
Please use this form and describe your issue, concisely but precisely, with as much detail as possible

Your Windows build number: (Type ver at a Windows Command Prompt)

Microsoft Windows [Version 10.0.17763.379]

What you're doing and what's happening: (Copy & paste specific commands and their output, or include screen shots)

In less, scrolling down (f) is instantaneous, but scrolling up (u) is extremely slow. For example, if I open man man and hold f, it takes about 1 second to scroll to the end, but if I hold u, it will take about 10 seconds to scroll back to the top.

Behavior is similar if I run less on a remote system through SSH, although in that case scrolling up gives the appearance of being 'jerkier'.

Issue 2:
repasting details from here:

Please use this form and describe your issue, concisely but precisely, with as much detail as possible

Please fill out the below information:

Version 1809 (OS Build 17763.195)

Summary

I updated to win10 ver 1809 today (previously ran 1803 without issue), and one of the first things i noticed is that when within using GNU screen the redraw is noticeably slower, when using caption value in .screenrc.

Environment

Here's the contents of an example $HOME/.screenrc:

caption always '%{= kw}[ %{y}%H%{-} ][ %= %-Lw%{+b M}%n%f* %t%{-}%+LW %= ][ %{r}%l%{-} ][ %{c}%c%{-} ]'

This is a pretty basic setting for screen to draw a floating "status bar" on the bottom showing what screen is selected, and is discussed on https://lizdenys.com/journal/articles/understanding-gnu-screens-captions.html

Only after i updated to 1809, i noticed that when launching GNU screen from within WSL (triggered via bash.exe), and doing something that requires the screen to re-draw scrolling text, the refresh rate is pretty slow (e.g. doing something like ls -l /usr/bin takes several seconds instead of being near instance when not using that setting in screen.

I've also tried resetting my environment entirely (wiping out all bash shell settings files e.g. $HOME/.bashrc and $HOME/.bash_profile). I narrowed it down to that captions always line being the culprit. I was first noticed how painful running ps auxwww was on a remote linux system :-(

What you're doing and what's happening:

generating output that exceeds the size of the window, resulting in scrolling behaviour. the redraw of the text from scrolling, results in a rate that makes me think i'm back on my first 486 computer

$ echo "caption always '%{= kw}[ %{y}%H%{-} ][ %= %-Lw%{+b M}%n%f* %t%{-}%+LW %= ][ %{r}%l%{-} ][ %{c}%c%{-} ]'" > .screenrc
$ screen
[... inside new screen ...]
$ ls -l /usr/bin

What's wrong / what should be happening instead:

time to perform a simple "dir" (via ls -l /usr/bin) takes ~20 seconds inside GNU screen

this same listing takes only a second and a half when not using GNU screen at all (or not using that captions always line in $HOME/.screenrc) .

whether or not using a screen multiplexer like GNU screen should not affect the refresh time, at least it didn't before i upgraded to win10 ver 1809 today.

Strace of the failing command, if applicable:

not applicable, running the ls comand using time reports nearly identical values:

outside of screen:

real 0m1.240s
user 0m0.016s
sys 0m0.063s

inside screen:

real 0m0.069s
user 0m0.000s
sys 0m0.063s

Which makes it seem that the comand isn't what's running any slower (in fact it reports it ran faster?) but the drawing the scrolling text is what's in-fact impacted.