File size is more than word count.
A long report made mostly of text is different from a short note carrying many embedded screenshots. Base64 image data lives inside the Markdown itself; big tables and long code blocks can also add work when the document is rendered.
In Finder, use Get Info to check the file size. Then inspect Source for long data:image/…;base64, references or unusually large blocks. See the image-storage comparison for a measured example of embedded-data overhead.
For a text correction, try Source.
Open the file in Zizeg—double-click it if Zizeg is your default Markdown app. Choose Source (⌘2) when you want to work directly with the Markdown text, or Split (⌘3) when the rendered result is useful alongside it.
If Split is your default viewing mode, both panes open automatically. Click the active Split control again to swap their order. For a small wording change, you can edit in Source and check Preview when it is ready.
Large documents can appear in stages.
Zizeg can show the beginning of Preview while the rest loads. During that process, Preview is temporarily read-only and synchronized scrolling is paused. Source remains editable, and its changes appear in Preview when loading finishes.
Some documents need to load in full before Preview becomes available. The time depends on the content and your Mac, so file size alone does not predict the experience.
Keep the content you need in a manageable form.
- For image-heavy files, consider separate image assets instead of embedding every picture in the Markdown.
- Resize oversized screenshots before adding them if the document only needs a smaller image.
- Break up a very large table or code block when separate sections make it easier to use.
- Split a document into related files when they are genuinely separate topics.
To try another image-storage format, use File → Save As… (⇧⌘S) and choose Assets Folder or Base64 Data URI. Zizeg prepares the converted copy without changing the original. Editing and export require a one-time unlock or an active subscription; reading is free.
If the file is easy to open but hard to navigate, start with headings, the outline, and Find.
