Notebooks: Why do they take forever to open?

[AlfredBaldenweck]

This has been bothering me for a while. Pro 3.5

Why do Notebooks in Pro take forever to open or load? For example, creating a new notebook in an otherwise empty project takes really long, and opening a project  with a notebook window open takes like 20 minutes sometimes.

What gives? Does anyone have a consistent solution for this?

[ShareUser · Accepted solution]

This is a known ArcGIS Pro issue (especially 3.4–3.5).

Why it’s slow

Pro notebooks spin up a full conda + Jupyter kernel every time.

Environment drift or partial package installs make validation painfully slow.

If a project opens with a notebook tab already open, Pro tries to restore the kernel this is often what causes 10–20 min startups.

Corporate antivirus scanning Python/conda folders makes it worse.

What actually helps

Never save projects with notebooks open → open notebooks after Pro fully loads.

Clone and use a fresh notebook environment (don’t overload the base env).

Avoid heavy imports or auto-running cells at startup.

Exclude ArcGIS/conda paths from antivirus if possible.

Use external Jupyter/VS Code for heavy work; keep Pro notebooks lightweight.

It’s an environment + kernel startup problem, not your machine and Pro 3.5 made it more noticeable.

[HaydenWelch]

To add to this, it's often better to not use the Jupyter kernel/notebooks in Pro. If I want an environment, I'll open a notebook/interactive window in VSCode and directly interact with my data from there.

I have a library I wrote called arcpie (https://github.com/hwelch-fle/arcpie) that's meant to make interaction with aprx and gdbs easier in simple interactive script files outside pro.

You can do this while the project is open too, you just won't be able to save from the script as the active Pro session will take priority for mapping operations. If you instead hook into the project from an interactive session and open the project read only you can watch the changes made in the interactive session.