When I am writing long-form, I use a three-pane technique setup:
Pane 1: Source mode for editing. Source mode is the fastest way to type into Obsidian since the markdown isn’t being formatted in any special way.
Pane 2: Preview mode to see rendering since the editing is happening in source mode.
Use the "Link with Tab" feature for panes 1 & 2. This keeps panes 1 and 2 synchronized while you edit.
Pane 3: for viewing other sections of a file while not losing the context while editing.
It looks like this:
Believe it or not, this speeds up typing, helps preview the markdown rendering, & maintains your context while writing.
Find out more about the Link with Tab: https://medium.com/obsidian-observer/obsidian-quick-tip-enhance-markdown-editing-with-link-with-tab-55a8b5c99177