High CPU usage and UI freezes when typing in .py files (Remote-SSH, Pylance enabled)

[G-Salviati]

Hi everyone,

I’ve been experiencing an issue since around March 5th.

I am working on a VM via VS Code Remote-SSH. I recently resumed work on a pytest suite designed to test Crossplane resources. Although the project is still very small—just one test file with a few tests—I am hitting major performance bottlenecks.

Environment & Dependencies

The project uses the following dependencies:

dependencies = [
    "boto3>=1.37.38",
    "jinja2>=3.1.6",
    "kubernetes>=34.1.0",
    "pytest>=8.3.5",
    "pytest-dependency>=0.6.0",
    "pytest-order>=1.3.0",
    "python-dotenv>=1.0.1",
    "pyyaml>=6.0.3",
    "tenacity>=9.0.0",
]

The Issue

As soon as I start typing in a .py file, I notice in htop that the VS Code server processes begin consuming excessive CPU. On this 2-core VM, the usage spikes from 1% to roughly 140% while typing. When I stop, it settles at around 40%.

After a few minutes of typing, VS Code starts freezing constantly. It stutters roughly every 7 seconds for about 2 seconds. This isn't limited to the editor; the entire UI freezes, including the terminal, the sidebar explorer, the top menu, and scrolling. The only way to temporarily resolve this is to kill the VS Code server processes and reconnect.

Troubleshooting Steps Taken

Extension Downgrade: I noticed the current version (v26.1.1) was released about 3 weeks ago. Since I last worked on this project 1.5 months ago without issues, I tried downgrading to a version from 3 months ago, but the behavior remained the same.

Configuration Tweaks: I tried to limit indexing and watchers using the following settings, but they didn't help:

settings.json

{
  "python.analysis.indexing": false,
  "python.analysis.userFileIndexingLimit": 500,
  "python.analysis.diagnosticMode": "openFilesOnly",
  "python.analysis.useLibraryCodeForTypes": false,
  "python.analysis.diagnosticDelay": 1000,
  "files.watcherExclude": {
        "**/.venv/**": true,
        "**/node_modules/**": true,
        "**/.git/**": true,
        "**/.*/**": true,
        "/proc/**": true,
        "/sys/**": true,
        "/dev/**": true
    },
    "search.followSymlinks": false,
    "python.testing.autoTestDiscoverOnSaveEnabled": false
}

pyrightconfig.json

{
    "executionEnvironments": [
        {
            "root": "."
        }
    ],
    "exclude": [
        "**/node_modules",
        "**/__pycache__",
        "**/.venv",
        "**/.*"
    ],
    "ignore": [
        "**/.venv"
    ],
    "reportMissingImports": false,
    "reportMissingModuleSource": false
}

Observations

The only way I can work without these freezes is by disabling the Pylance extension. As soon as Pylance is off, the CPU usage returns to normal.

Since I’d really like to keep the features provided by Pylance, do you have any suggestions on what might be causing this or how to fix it?

[github-actions]

Hi @G-Salviati, I'm an AI Support assistant here to help with your issue. While the team reviews your request, I wanted to provide some possible tips and documentation that might help you in the meantime.

---

Potential Duplicate Issues – These issues may be duplicates of your report, but may differ in some of the details.

• pylance consumes 100% CPU in remote-ssh environment – CPU spikes on remote SSH due to endless file system loops and large directory scans; suggests excluding problematic folders via pyrightconfig.json. pylance consumes 100% CPU in remote-ssh environment #1939
• Pylance is using over 100% CPU – CPU spikes caused by indexing all site-packages and workspace files; workaround: narrow analysis scope or disable python.analysis.useLibraryCodeForTypes. Pylance is using over 100% CPU. #201
• Pylance doesn’t stop analyzing files – fixed UI bug causing continuous analysis and high CPU; updating to the latest Pylance version resolves. Pylance doesn't stop analyzing files #5867

---

Potential Workarounds:

• Exclude large or unnecessary paths from analysis:
  In your workspace .vscode/settings.json:

  {
    "python.analysis.exclude": [
      "**/site-packages/**",
      "**/.venv/**",
      "**/__pycache__/**",
      "**/node_modules/**",
      "**/your_large_build_folder/**"
    ]
  }

  Or in pyrightconfig.json:

  {
    "exclude": [
      "**/site-packages",
      "**/.venv",
      "**/your_large_build_folder"
    ]
  }

• Disable or reduce indexing and library type analysis:

  {
    "python.analysis.indexing": false,
    "python.analysis.useLibraryCodeForTypes": false
  }

• Limit diagnostics to open files only:

  {
    "python.analysis.diagnosticMode": "openFilesOnly"
  }

The team will respond to your issue shortly. Please note this is a trial feature and may not be fully accurate. I hope these suggestions are helpful in the meantime. If this comment helped you, please give it a 👍. If the suggestion was not helpful or was incorrect, please give it a 👎. Your feedback helps us improve!

[rchiodo]

Thanks for the issue. We do have something that might indicate what the problem is.

There's a way to profile Pylance:

Pylance: Start Profiling with use the nodejs profiler to capture a CPU profile of Pylance's usage. However it doesn't capture anything that should cause problems with the UI, especially in a remote situation.

You might instead use the builtin extension profiler that VS code has:

Then you click on the little black button:

That will profile the extension host. You'd reproduce your problem, then click the red square button.

That should generate a CPU Profile (after you click save) that you can upload here.

I suspect something is slow in VS code though. It might have to do with parsing the data returned across the remote.

[viktortoenkoel]

@G-Salviati disable pylance and install pyright it does the most important things without any excess cpu usage.

I have the same issue, python file is 500lines, in a repository of ~20k lines, ssh remote setup.