Codex CLI slow startup / severe input lag (Possibly since 0.84, possibly related to IO / FileProvider churn)

Thanks for the report. I don't think we've observed this or received any other reports of this yet. We'll likely need some additional help from you to pin down the problem. You mentioned that you saw this first with 0.84. What was the last version where this didn't occur?

Thanks for the response @etraut-openai
It seems to have started after upgrading from 0.81 to 0.84, but as I said, downgrading did not seem to fix it so I can't quite say for certain it's version specific

As I mentioned, we haven't received any other reports of this, so it must be something specific to your system or configuration.

Here's a thought... maybe it's related to some large or corrupt state in your ~/.codex directory. Try renaming that directory temporarily and see if that clears it up. You'll need to log in again after the rename.

Hi @etraut-openai - yep, that was indeed a my-machine issue. Wrong guess on my part:)
Resetting the .codex folder fixed it.

It seemed to have been related to the shell snapshot, in combination with the fact I had recently added a program that runs automatically during shell init that expects an interactive TTY and is a tiny bit slow to boot. So, yeah, not the most common setup.

That caused repeated snapshot timeouts and a humongous log file. the lag went away once I gated that program to real interactive terminals (which is what it should have been doing anyway 🫣).

Could have guessed that sooner, but it took a while for the logs to grow big enough to cause the TUI issues.

Just a bit of post-mortem info in case it's useful with my guess of what happened

Config context from ~/.codex/config.toml which I think is relevant:

sandbox_mode = "workspace-write"

[features]
rmcp_client = true
unified_exec = true
shell_snapshot = true

[shell_environment_policy]
experimental_use_profile = true
inherit = "core"
include_only = [
  "PATH",
  "HOME",
  "SHELL",
  "USER",
  "TMPDIR",
  "LANG",
  "LC_ALL",
  "TERM",
  "ASDF_NODEJS_LEGACY_FILE_DYNAMIC_STRATEGY",
  "ASDF_RUBY_VERSION",
]
# just to be extra extra safe 
exclude = ["*_API_KEY", "*_TOKEN", "*_SECRET", "*PASSWORD*"]

Problematic file growth in ~/.codex:

• ~/.codex/log/codex-tui.log was 219M with 1,052,359 lines.
• After fixing the shell init and resetting state, ~/.codex/log/codex-tui.log is ~23K (well, since I reset it, makes sense)

Log excerpts showing the timeouts (from the large log):

2026-01-15T14:48:57.756156Z  WARN codex_core::shell_snapshot: Failed to create shell snapshot for zsh: Snapshot
command timed out for zsh
2026-01-15T14:49:16.881015Z  WARN codex_core::shell_snapshot: Failed to create shell snapshot for zsh: Snapshot
command timed out for zsh
2026-01-15T14:50:36.714680Z  WARN codex_core::shell_snapshot: Failed to create shell snapshot for zsh: Snapshot
command timed out for zsh

Related TUI errors around the same timestamps:

2026-01-15T14:48:57.761750Z ERROR codex_tui::chatwidget::agent: failed to submit op: internal error; agent loop died
unexpectedly
2026-01-15T14:49:17.034346Z ERROR codex_tui::app_event_sender: failed to send event: channel closed

Thanks for sharing the analysis. That's helpful in case other users run into a similar situation.

hi there, i just installed codex on windows and there is indeed severe input lag when typing

yes a bit laggy for me too on windows

Agreed on both windows AND linux vps

Very laggy on windows and on Weztem, input lag is really bad

Running a bit better in wsl

I hit the same input lag and tracked it down to the paste-burst heuristic in the TUI. On every plain ASCII keystroke, codex holds the character for a short interval (8 ms on Unix, 30 ms on Windows) trying to detect whether it's the start of a paste.

Disabling it fixed the lag for me completely. Add this to ~/.codex/config.toml:

disable_paste_burst = true

Input lag on Ubuntu too