performance improvements (#116)

closes #111

doc/diffs.nvim.txt

@@ -52,7 +52,6 @@ Configuration is done via `vim.g.diffs`. Set this before the plugin loads:
 >lua
     vim.g.diffs = {
       debug = false,
-      debounce_ms = 0,
       hide_prefix = false,
       highlights = {
         background = true,
@@ -109,11 +108,6 @@ Configuration is done via `vim.g.diffs`. Set this before the plugin loads:
                              Enable debug logging to |:messages| with
                              `[diffs]` prefix.
 
-        {debounce_ms}        (integer, default: 0)
-                             Debounce delay in milliseconds for re-highlighting
-                             after buffer changes. Lower values feel snappier
-                             but use more CPU.
-
         {hide_prefix}        (boolean, default: false)
                              Hide diff prefixes (`+`/`-`/` `) using virtual
                              text overlay. Makes code appear without the
@@ -611,7 +605,7 @@ Summary / commit detail views: ~
      priority 201 overlay changed characters with an intense background
    - Conceal extmarks hide diff prefixes when `hide_prefix` is enabled
    - All priorities are configurable via |diffs.PrioritiesConfig|
-4. Re-highlighting occurs on `TextChanged` (debounced) and `Syntax` events
+4. A decoration provider re-highlights visible hunks on each redraw
 
 Diff mode views: ~
 1. `OptionSet diff` detects when any window enters diff mode
@@ -637,14 +631,8 @@ the buffer briefly shows fugitive's default diff highlighting before
 diffs.nvim applies treesitter highlights.
 
 This occurs because diffs.nvim hooks into the `FileType fugitive` event,
-which fires after vim-fugitive has already painted the buffer. Even with
-`debounce_ms = 0`, the re-painting goes through Neovim's event loop.
-
-To minimize the flash, use a low debounce value: >lua
-    vim.g.diffs = {
-      debounce_ms = 0,
-    }
-<
+which fires after vim-fugitive has already painted the buffer. The
+decoration provider applies highlights on the next redraw cycle.
 
 Conflicting Diff Plugins ~
                                                     *diffs-plugin-conflicts*