DEV: Add a watched-words/mini_racer perf regression spec (#26341)

/t/121361

spec/lib/pretty_text_spec.rb

@@ -1954,6 +1954,39 @@ HTML
   describe "watched words - replace & link" do
     after { Discourse.redis.flushdb }
 
+    # Makes sure that mini_racer/libv8-node env doesn't regress
+    it "finishes in a timely matter" do
+      sql = 1500.times.map { |i| <<~SQL }.join
+        INSERT INTO watched_words
+        (created_at, updated_at, word, action, replacement)
+        VALUES
+        (
+          :now,
+          :now,
+          'word_#{i}',
+          :action,
+          'replacement_#{i}'
+        );
+      SQL
+
+      DB.exec(sql, now: Time.current, action: WatchedWord.actions[:replace])
+
+      Fabricate(
+        :watched_word,
+        action: WatchedWord.actions[:replace],
+        word: "nope",
+        replacement: "yep",
+      )
+
+      # Due to a bug in node 18.16 and lower this takes about 11s.
+      # On node 18.19 and newer it takes about 250ms
+      expect do
+        Timeout.timeout(3) do
+          expect(PrettyText.cook("abc nope def")).to match_html("<p>abc yep def</p>")
+        end
+      end.not_to raise_error
+    end
+
     it "replaces words with other words" do
       Fabricate(
         :watched_word,