vim lazyredraw for a batch-editing workload: which redraw behavior should stay enabled

Direct answer

lazyredraw applies to every scripted screen update, not just macros and mappings. It postpones the physical screen paint for the duration of any command, macro, or script, including :normal, :global, and :substitute. An explicit :redraw inside a plugin will override it, and there is no built-in way to scope that. ttyfast is not worth setting on a modern local terminal; it is a no-op in this context.

What lazyredraw actually covers

lazyredraw is not limited to interactive macros. It defers screen updates for the duration of a single command, macro, or script execution. This applies uniformly to :normal, :global, :substitute, and other Ex commands run from scripts or the command line. The option is about the physical screen paint, not buffer-content changes. In non-interactive use (vim -es, -c, -S, or Ex mode), Vim often skips screen updates entirely unless :redraw is invoked, making lazyredraw largely redundant. The option matters most in interactive macro/script runs where the UI stays visible.

Plugin redraws and lazyredraw

An explicit :redraw (or :redraw!) forces an immediate screen update regardless of lazyredraw. Plugins that call :redraw will bypass the deferral; there is no built-in mechanism to suppress or scope a plugin's :redraw short of patching the plugin or wrapping its calls. If your scratch-buffer plugin calls :redraw during initialization, it will force a redraw. The only way to prevent this is to patch the plugin or wrap its calls. If the plugin uses :redraw! (force redraw including status lines), it cannot be silenced by configuration; consider filing an upstream issue or forking if the redraw is costly.

ttyfast on a modern local terminal

ttyfast tells Vim the terminal can handle fast output (e.g., no padding delays). On a modern local terminal (Linux console, xterm, Wayland terminal emulators) it has no measurable effect in batch mode because Vim already detects a fast terminal and because batch scripts typically run with 'silent' or redirected output where terminal capabilities are irrelevant. In batch context, ttyfast is a no-op.

Verification

To confirm no other script overrides lazyredraw or ttyfast, check :verbose set lazyredraw? ttyfast?. To profile the effect of lazyredraw, run vim --startuptime /tmp/vim.log -S yourscript.vim and compare elapsed time with and without lazyredraw; on batch workloads the difference is typically <1%.

Summary

lazyredraw applies uniformly to scripted screen updates, including :normal, :global, and :substitute. An explicit :redraw in a plugin will override it. ttyfast is not worth setting on a modern local terminal.