GeezerVison is showing github.com — Very slow performance opening layouts/workspaces · Issue #1053 · tmux-python/tmuxp
Very slow performance opening layouts/workspaces #1053DescriptionI used to use this project a while ago, recently I wanted to incorporate it again in a few of my scripts but it seems like opening layouts takes a significant amount of time.
Simple layouts (2 windows where 1 window is a split pane with simple commands prefilled) can take several seconds to open. It seems to linearly scale with the amount of windows as well.
This feels like something that should take milliseconds, not seconds.
Here is an extreme example of a workspace that took 25 seconds!
✓ Loaded workspace: work/haystack (~/.config/tmux-layouts/projects/work/haystack/layout.yaml) [12 win, 18 panes]
Session created in detached state.
[detached (from session work/haystack)]
~ took 25s
Repeat the following windows 6 times (for 12 total windows) and you've got the layout from above:
session_name: ${SESSION_NAME}
start_directory: ${PROJECT_DIR}
windows:
- window_name: Editor
layout: main-vertical
focus: true
options:
main-pane-width: 75%
panes:
- shell_command: nvim
focus: true
- null
- panes:
- null
It's especially jarring because I feel like it definitely did not take this long with a version from months ago, though I can't say that with certainty.
This project so far does provide the most flexibility and features that I'd like to have, so thanks for the effort! <3 Activitymoustachioed commented on Jun 22, 2026 I can confirm that there is a severe regression in performance somewhere between version 1.56.0 and 1.67.0. After my system update loading my sessions (maybe 5-6 windows with 1 pane each per session) went from roughly 1 second per session to at least 10 seconds each. tony commented on Jun 26, 2026 Will look closer this weekend. WIP: #1056 / tmuxp-lag tony commented on Jun 27, 2026 tony commented on Jun 29, 2026 If you try tmuxp 1.73.0, and do this in your workspace file:
workspace_builder_options:
pane_readiness: never Is it any faster? moustachioed commented on Jun 29, 2026 @tony I can confirm both, 1.64.0 and 1.73.0 with the additional option are much faster. Thanks for your fix! DrunkenToast commented on Jul 3, 2026 Can confirm it is much faster. Went from 25s to 7s however for something that seemingly just has to open a session and set up windows with some prefilled commands this still feels slow. Of course I don't know much about the implementation so I don't want to cast judgement, just a surface level feeling :)
It's mostly because I felt like in the past it was almost instant that I opened this ticket. I think if it was 7 seconds from the get go that I would've opened this ticket as well. But I could be misremembering things.
Much appreciated for the quick action though! <3 tony commented on Jul 5, 2026
Can confirm it is much faster. Went from 25s to 7s however for something that seemingly just has to open a session and set up windows with some prefilled commands this still feels slow. Of course I don't know much about the implementation so I don't want to cast judgement, just a surface level feeling :)
Yes. tmuxp will soon go from the slowest session launcher to the fastest, while staying featureful and pythonic.
This is a preview from a future update, for an upcoming release:
┌─────────────────┬───────┬────────────────┬───────────────────┬─────────┐
│ Workspace │ panes │ classic median │ engine-ops median │ speedup │
├─────────────────┼───────┼────────────────┼───────────────────┼─────────┤
│ 1 win × 1 pane │ 1 │ 739 ms │ 20 ms │ 37× │
├─────────────────┼───────┼────────────────┼───────────────────┼─────────┤
│ 1 win × 4 panes │ 4 │ 2.56 s │ 32 ms │ 79× │
├─────────────────┼───────┼────────────────┼───────────────────┼─────────┤
│ 3 win × 3 panes │ 9 │ 5.80 s │ 60 ms │ 97× │
├─────────────────┼───────┼────────────────┼───────────────────┼─────────┤
│ 5 win × 4 panes │ 20 │ 12.70 s │ 150 ms │ 85× │
├─────────────────┼───────┼────────────────┼───────────────────┼─────────┤
│ 8 win × 4 panes │ 32 │ 23.13 s │ 298 ms │ 78× │
└─────────────────┴───────┴────────────────┴───────────────────┴─────────┘
tony commented on Jul 5, 2026 To show it's not just talk - note this could break, the ultimate PR I go with may end up being different. I'll be working on it over the next few weeks:
If you're feeling bold and have uv installed:
uvx --from git+https://github.com/tmux-python/tmuxp.git@engine-ops \
tmuxp load \
--engine-ops \
<path-to-workspace-or-workspace-file> Does this work? DrunkenToast commented on Jul 6, 2026
To show it's not just talk - note this could break, the ultimate PR I go with may end up being different. I'll be working on it over the next few weeks:
* [feat: engine-ops async folding workspace builder #1075](https://github.com/tmux-python/tmuxp/pull/1075)
If you're feeling bold and have uv installed:
uvx --from git+https://github.com/tmux-python/tmuxp.git@engine-ops
tmuxp load
--engine-ops
Does this work?
I just tried it and it's definitely an impressive difference for startup! I think it's max a second or so now.
Thanks for sharing! :)
P.S. I don't know how far development got along here but I did notice that commands executing takes a while once opened, gut feeling is like 3 seconds before it starts opening vim for example, and I think it is ignoring the enter: false option. Reacted by Tony Narlock Reacted by Tony Narlock tony commented on Jul 7, 2026
I just tried it and it's definitely an impressive difference for startup! I think it's max a second or so now.
Thank you to trying it!
P.S. I don't know how far development got along here but I did notice that commands executing takes a while once opened, gut feeling is like 3 seconds before it starts opening vim for example, and I think it is ignoring the enter: false option.
I will investigate this angle. It's not too late to look at / reenvision anything.
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