fix: sluggish mouse scroll

markdown.go

@@ -13,6 +13,7 @@ import (
 )
 
 var commentMarkdownRenderers sync.Map
+var commentMarkdownLines = newMarkdownLineCache(512)
 var quoteRailStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("#777777"))
 var markdownStyleName = "dark"
 var renderedMentionPattern = regexp.MustCompile(
@@ -20,12 +21,63 @@ var renderedMentionPattern = regexp.MustCompile(
 )
 var sgrPattern = regexp.MustCompile(`\x1b\[[0-9:;]*m`)
 
+type markdownLineCacheKey struct {
+	markdown string
+	width    int
+}
+
+type markdownLineCache struct {
+	mu      sync.Mutex
+	limit   int
+	entries map[markdownLineCacheKey][]string
+	order   []markdownLineCacheKey
+}
+
+func newMarkdownLineCache(limit int) *markdownLineCache {
+	return &markdownLineCache{
+		limit: limit, entries: make(map[markdownLineCacheKey][]string),
+	}
+}
+
+func (c *markdownLineCache) get(key markdownLineCacheKey) ([]string, bool) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	lines, ok := c.entries[key]
+	return append([]string(nil), lines...), ok
+}
+
+func (c *markdownLineCache) put(key markdownLineCacheKey, lines []string) []string {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	if cached, ok := c.entries[key]; ok {
+		return append([]string(nil), cached...)
+	}
+	if len(c.entries) >= c.limit {
+		delete(c.entries, c.order[0])
+		c.order = c.order[1:]
+	}
+	c.entries[key] = append([]string(nil), lines...)
+	c.order = append(c.order, key)
+	return append([]string(nil), lines...)
+}
+
+func (c *markdownLineCache) clear() {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	c.entries = make(map[markdownLineCacheKey][]string)
+	c.order = nil
+}
+
 func renderCommentMarkdown(markdown string, width int) []string {
 	if strings.TrimSpace(markdown) == "" {
 		return nil
 	}
 	width = max(10, width)
 	markdown = normalizeGitHubAlerts(markdown)
+	cacheKey := markdownLineCacheKey{markdown: markdown, width: width}
+	if lines, ok := commentMarkdownLines.get(cacheKey); ok {
+		return lines
+	}
 	var (
 		result     []string
 		block      []string
@@ -64,7 +116,7 @@ func renderCommentMarkdown(markdown string, width int) []string {
 		block = append(block, content)
 	}
 	flush()
-	return trimMarkdownLines(result)
+	return commentMarkdownLines.put(cacheKey, trimMarkdownLines(result))
 }
 
 func renderMarkdownFragment(markdown string, width int) []string {