perf: avoid goquery PrevAll/Text in list whitespace heuristic (#2)

* perf: avoid goquery PrevAll/Text in list whitespace heuristic (huge speedup on large HTML)

* add perf testcase

Author: abimaelmartell

commonmark.go

@@ -100,9 +100,9 @@ func (c *Converter) InitializeCommonMarkRules() []Rule {
 				// if its inside a list, trim the spaces to not mess up the indentation
 				parent := selec.Parent()
 				next := selec.Next()
-				if IndexWithText(selec) == 0 &&
-					(parent.Is("li") || parent.Is("ol") || parent.Is("ul")) &&
-					(next.Is("ul") || next.Is("ol")) {
+				if (parent.Is("li") || parent.Is("ol") || parent.Is("ul")) &&
+					(next.Is("ul") || next.Is("ol")) &&
+					isFirstNonEmptyListTextNode(selec) {
 					// trim only spaces and not new lines
 					text = strings.Trim(text, ` `)
 				}

perf_big_html_test.go

@@ -0,0 +1,39 @@
+package md_test
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	md "github.com/firecrawl/html-to-markdown"
+)
+
+// TestPerfBigHTML_Smoke runs a large HTML file (random-ish content),
+// converts it once, and asserts we get non-empty output.
+//
+// This is intentionally a "smoke" perf test: no golden output, just "it renders".
+// Run it alone to track timings over time:
+//
+//	go test -run '^TestPerfBigHTML_Smoke$' -count=1
+func TestPerfBigHTML_Smoke(t *testing.T) {
+	p := filepath.Join("testdata", "Perf", "big.html")
+
+	if _, err := os.Stat(p); err != nil {
+		p = filepath.Join("testdata", "Perf", "test.html")
+	}
+	b, err := os.ReadFile(p)
+	if err != nil {
+		t.Fatalf("read %s: %v", p, err)
+	}
+	html := string(b)
+
+	conv := md.NewConverter("", true, nil)
+	out, err := conv.ConvertString(html)
+	if err != nil {
+		t.Fatalf("convert: %v", err)
+	}
+	if strings.TrimSpace(out) == "" {
+		t.Fatalf("expected non-empty markdown output")
+	}
+}