CLAUDE_CODE_SLOW_OPERATION_THRESHOLD_MS

Updated October 13, 2026 by Alex Sorokoletov

CLAUDE_CODE_SLOW_OPERATION_THRESHOLD_MS is a Claude Code environment variable: Threshold for slow filesystem operation warnings. Present since v2.1.69 or earlier and still present in v2.1.294. It is not in the official reference.

Status	Present in v2.1.294
Added	Present since v2.1.69 or earlier
Category	Other
Official docs	Not listed

How to set it

For one session, export it in the shell that starts Claude Code:

export CLAUDE_CODE_SLOW_OPERATION_THRESHOLD_MS=<value>
claude

To apply it to every session, add it to the env object of a settings file:

// ~/.claude/settings.json
{
  "env": {
    "CLAUDE_CODE_SLOW_OPERATION_THRESHOLD_MS": "<value>"
  }
}

Release notes that mention it

Claude Code v2.1.74 — 2 New Environment Variables: Frame Timing & Session End Hooks

Related variables

CLAUDE_CODE_IDLE_THRESHOLD_MINUTES: Sets the threshold (in minutes) before a session is considered idle.
CLAUDE_SLOW_FIRST_BYTE_MS: Default 30,000ms.
ANTHROPIC_BETAS: Comma-separated beta feature headers.
ANTHROPIC_CUSTOM_HEADERS: Custom HTTP headers (newline-separated Key: Value).
ANTHROPIC_FEDERATION_RULE_ID
ANTHROPIC_ORGANIZATION_ID
ANTHROPIC_WORKSPACE_ID
BETA_TRACING_ENDPOINT: Custom endpoint for beta tracing.

Frequently asked questions

What does CLAUDE_CODE_SLOW_OPERATION_THRESHOLD_MS do?

Threshold for slow filesystem operation warnings

Which Claude Code version has CLAUDE_CODE_SLOW_OPERATION_THRESHOLD_MS?

Present since v2.1.69 or earlier and still present in v2.1.294.

How do I set CLAUDE_CODE_SLOW_OPERATION_THRESHOLD_MS?

Export it before starting Claude Code (export CLAUDE_CODE_SLOW_OPERATION_THRESHOLD_MS=value), or add it to the "env" object in ~/.claude/settings.json to apply it to every session.

All variables, searchable: Claude Code environment variables.