TikZ externalization vs. inline rendering for figure-heavy documents without shell escape

In environments where shell-escape is disabled, the choice between TikZ externalization and inline rendering depends on whether you prioritize build speed or visual correctness for complex layouts.

For documents heavily utilizing remember picture and overlay, inline rendering is the recommended fallback. While externalization via mode=list can offer speed benefits by pre-compiling figures, its isolation nature often breaks features that rely on the global document state to calculate coordinates.

The Problem with Externalization without Shell Escape

When shell-escape is restricted, the TikZ external library cannot automatically trigger the TeX engine to process figures. To bypass this, you must use externalize [mode=list], which generates a Makefile. This introduces several complexities:

Environment Dependency: It requires a Unix-like environment with GNU `make installed.

Isolation Issues: Each figure is compiled as a standalone document. Features like remember picture require the engine to know the final page layout to position elements correctly. In an isolated compilation, these coordinates are often zeroed out or incorrect.

Stale Content: If the document text changes (moving a figure), the external PDF may not update unless the Makefile is manually cleared or re-run correctly.

When to Stick with Inline Rendering

Inline rendering is the most stable approach for no-shell-escape environments because it processes the TikZ code as part of the main compilation pass. This ensures:

• Correctness: overlay and remember picture have full access to the global document state.
• Simplicity: No external build tools or complex flags are required.
• Performance: The only downside is speed; every figure is re-rendered on every compile, which becomes prohibitive in large documents.

Balanced Strategy for Large Documents

If inline rendering is too slow but you cannot use shell-escape externalization, consider these hybrid strategies:

1. Manual Externalization: Move complex TikZ figures into separate standalone LaTeX files. Compile them once manually and use \include in the main document. This gives you the speed of external PDFs without the TikZ library's automation logic.
2. Conditional Compilation: Use a \if toggle to comment out heavy TikZ code during iterative text editing, and uncomment it only for the final production build.

Diagnostic Question: Does your document rely on remember picture to position figures relative to specific text nodes nodes, or are the figures mostly self-contained diagrams?