Troubleshoot analyzer performance

This guide helps you diagnose and resolve common Dart analysis server performance issues in your Dart or Flutter IDE.

Several common issues significantly hurt the performance of the Dart analysis server (the analyzer). Check the following issues to see if they might be impacting your development environment.

On Windows systems, if Windows Defender (or other real-time security software) is enabled, it can slow down the file read times enough to impact analyzer performance. The analyzer frequently reads files, and constant scanning can introduce latency. To mitigate this, you can set up exclusions for the directories the analyzer reads from.

If you choose to set up exclusions, include the following directories:

• The analysis server's cache directory: %LOCALAPPDATA%\.dartServer
• The directory for packages downloaded by pub: %LOCALAPPDATA%\Pub\Cache
• Any other directories containing code for your applications.

For another way to improve file I/O performance, consider setting up a dev drive.

If your package directory contains symbolic links that point to a location inside the same directory, or to a parent directory, you might experience performance problems with Dart tooling (like the analyzer).

Status: The Dart team is actively working on a fix for this issue.

Workaround: There are no known workarounds at this time.

If the known issues don't seem to apply to your situation, please open an issue in the Dart SDK issue tracker. The more information you provide, the faster the team can diagnose and fix the problem.

In your issue, please provide detailed steps to reproduce the behavior you're observing.

1. If you're working on an open-source project, include instructions for downloading the code.
2. If you can't share your code, create a small, self-contained reproduction case.
3. If you can't provide either, please state that in the issue.

If the issue is related to performance, providing performance data can be very helpful. You can collect this data using the analysis server's diagnostic pages:

1. Open the Analyzer Diagnostics page:
   • If you are using VS Code:
     1. Click View > Command Palette.
     2. Type Dart: Open Analyzer Diagnostics and select it.
   • If you are using IntelliJ / Android Studio:
     1. Open the Dart Analysis tool window.
     2. Click the settings icon, and then select View analyzer diagnostics.
2. Collect the report:
   1. In the browser page that opens, click Collect Report in the top banner.
   2. Perform the actions that trigger the slow behavior.
   3. Click the Download report link.
3. Attach the report to your issue.

In some cases, instrumentation logs can provide additional details for diagnosing issues.

To capture these logs:

• VS Code: Follow the instructions for capturing analyzer instrumentation logs.
• IntelliJ / Android Studio: Follow the analyzer instrumentation instructions.

Before attaching logs to a GitHub issue, review them carefully to ensure they do not contain any personal, sensitive, or proprietary information.