Under remote (ssh) GNU screen and tmux sessions large output causes horrible performance

[jblaine]

Environment

Windows build number: Microsoft Windows [Version 10.0.18363.959]
Windows Terminal version (if applicable): 1.1.2021.0

Windows 10 native ssh client
Remote Linux host running either tmux or GNU screen, multiple versions all work to reproduce issue

Steps to reproduce

ssh to a host
run screen or tmux or attach to an existing session of either
run cat on a large text file, such as one with 3000+ lines

Expected behavior

Terminal should display a somewhat consistent stream of text, like PuTTY, Powershell on its own, CMD.EXE on its own, and other tools do.

Actual behavior

Terminal displays a little, pauses for several seconds, displays some more, pauses, etc

[zadjii-msft]

Correct me if I'm wrong, but how is this different from #7019? It might be best to merge this discussion with that thread.

• Does this repro without tmux/screen running on the remote host?
• Does this repro with the ssh from a WSL distro?
• More insane - if you run wsl.exe ssh.exe <args to ssh...> inside a legacy powershell/cmd window, does the same issue repro? This will cause wsl to create a conpty to host ssh.exe, which could help identify if the issue is conpty vs something else.

I'm also thinking this might be related to conpty buffering the frames to at least 1/60th of a second, maybe something weird in this situation is causing that delay to seem much larger

[jblaine]

Sure, I'm fine merging my comments over there. The info in #7019 seemed a little different to me at the time I created this.

I'll close this in favor of #7019