Two costs on the gutter's hot path:
The margin rebuilt its document-line -> glyph map on every Render, resolving
each bookmark by scanning the document's reference segments. A scroll, a hover,
or the 600 ms post-navigation pulse repaints many times a second, so this
rescanned the references per bookmark per frame. Compute the map once and reuse
it, clearing the cache only when the document or the bookmark set changes (the
model's DebugInfo/References are set before the text, so the document-change
hook sees them current).
CanToggleBookmarkAtLine, called for every gutter line the pointer moves over,
built a full bookmark including a captured editor view state -- a foldings
snapshot, scroll offsets, and a tree-path walk -- only to test it for null. It
now does an anchor-only check; the view state is captured only when a bookmark
is actually created.
Assisted-by: Claude:claude-opus-4-8:Claude Code
Siegfried Pammer
2846f00080