X11 forwarding extremely slow (unusable) after Cygwin upgrade (starting from cygwin1.dll version 3.1.0-0.4)

[Ken Brown]

[Please don't top-post on this list.]

On 1/2/2020 4:25 PM, ianpul01@gmail.com wrote:
> Now narrowed down to cygwin1.dll version 3.1.0-0.4 as the release which
> introduced this issue.
> 
> I found the intervening versions between 3.0.7-1 and 3.1.0-1 as test
> releases in earlier release archives at crouchingtigerhiddenfruitbat.org, so
> incrementally installing those from 3.1.0-0.1, I found that with cygwin1.dll
> version 3.1.0-0.3 X11 forwarding works fine, with 3.1.0-0.4 it is extremely
> slow (unusably slow for CPU-intensive programs).

I think this narrows it down to one of the following commits:

commit b7e429420063264d0be7ee6804f3e6f143f66232
Author: Takashi Yano <takashi.yano@nifty.ne.jp>
Date:   Thu Sep 5 19:44:41 2019 +0900

     Cygwin: pty: Fix potential state mismatch regarding pseudo console.

commit 915fcd0ae8d83546ce135131cd25bf6795d97966
Author: Takashi Yano <takashi.yano@nifty.ne.jp>
Date:   Thu Sep 5 13:22:54 2019 +0900

     Cygwin: pty: Fix select() with pseudo console support.

commit 433c6b8e0a667f9eae41a52efadec35ac62730df
Author: Takashi Yano <takashi.yano@nifty.ne.jp>
Date:   Thu Sep 5 09:24:26 2019 +0900

     Cygwin: pty: Disable clear screen on new pty if TERM=dumb or emacs*.

commit d4045fdbef60d8e7e0d11dfe38b048ea2cb8708b
Author: Takashi Yano <takashi.yano@nifty.ne.jp>
Date:   Wed Sep 4 22:47:42 2019 +0900

     Cygwin: pty: Add a workaround for ^C handling.

commit 83b2d576c835dad6b8e2ea53b55a25e7bfcdcde7
Author: Takashi Yano <takashi.yano@nifty.ne.jp>
Date:   Wed Sep 4 22:46:51 2019 +0900

     Cygwin: pty: Limit API hook to the program linked with the APIs.

commit 583102e7c9255ae25310154995f855e4f573f81c
Author: Takashi Yano <takashi.yano@nifty.ne.jp>
Date:   Wed Sep 4 10:45:35 2019 +0900
     Cygwin: pty: Fix state management for pseudo console support.

commit ffbb9b49711f6a8e3c4f83b226ff9476327dcb61
Author: Takashi Yano <takashi.yano@nifty.ne.jp>
Date:   Wed Sep 4 10:44:25 2019 +0900

     Cygwin: pty: Move function hook_api() into hookapi.cc.

commit bddb018e10e90ea300537d5a13999558b7dce476
Author: Takashi Yano <takashi.yano@nifty.ne.jp>
Date:   Wed Sep 4 10:44:24 2019 +0900

     Cygwin: pty: Speed up a little hooked Win32 API for pseudo console.

commit 9adb260181fa148fad0e91c55e41ea6d75eb8eb8
Author: Takashi Yano <takashi.yano@nifty.ne.jp>
Date:   Wed Sep 4 10:44:23 2019 +0900

     Cygwin: pty: Code cleanup

Ken
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