ipykernel 7.0.1 - Jupyter autocomplete delay

**Issue:**
When using VS Code with the Jupyter extension, triggering autocomplete (`Ctrl + Space`) inside a notebook cell causes a noticeable delay (~2–3 seconds). This only happens in Jupyter notebooks, regular `.py` files are unaffected.

**Steps to reproduce:**

1. Open a Jupyter notebook in VS Code.
2. Import any Python module (e.g., `import pandas as pd`).
3. Inside a new cell, type something like `pd.` and press `Ctrl + Space`.
4. Observe a 2–3 second delay before suggestions appear.

**Expected behavior:**
Autocomplete should appear instantly, as it does in `.py` files.

Reverting ipykernel to version **6.30.1** immediately fixes the issue.