---
id: TASK-032
title: Memoize editor visual model — fix scroll/open lag
status: "\U0001F3C1 Done"
assignee: []
created_date: '2026-06-30 20:44'
updated_date: '2026-06-30 20:44'
labels:
  - bug
  - performance
dependencies: []
priority: high
ordinal: 31000
---

## Description

<!-- SECTION:DESCRIPTION:BEGIN -->
buildVisual() rescanned+rewrapped+restyled the whole document on every View, cursor move, and scroll tick (no caching). Per single scroll row: 20ms/62MB at 500 lines, 133ms/345MB at 2000 lines w/ spell. Caused open-doc lag and scroll stutter. Fix: memoize the scan+wrap model (e.visual []vrow), invalidate only on scan/wrap input changes (Lines/Width/theme/spell/codeFile). Scroll/render now O(visible) ~0.4ms, independent of doc size.
<!-- SECTION:DESCRIPTION:END -->

## Acceptance Criteria
<!-- AC:BEGIN -->
- [ ] #1 Scroll + render reuse cached visual model (buildCount<=1 across scroll loop)
- [ ] #2 Edits/theme/spell/width changes invalidate cache (no stale render)
- [ ] #3 All tests pass
<!-- AC:END -->