Maybe markup messed up in your comment?

The real tests look like this:

      doc1 = "More (XXXXX) to muck up reg.*{99} [solutions]+";
      doc2 = "More (stuff) to muck up reg.*{99} [solutions]+";
      assertTrue(test(doc1,doc2));
      
      doc1 = "More (XXXXX) to muck up reg.*{99} [solutions]+";
      doc2 = "More (stuff) to muck up regZ*{99} [solutions]+";
      assertFalse(test(doc1,doc2));

      doc1 = "More ^XXXXX) to muck up reg.*{99} [solutions]+";
      doc2 = "More ^stuff) to muck up reg.*{99} [solutions]+";
      assertTrue(test(doc1,doc2));

spoiler flag... ;p

no, not efficient enough: you need a solution with O(1) time complexity (meaning: no loop at all).

I guess you try to build all the points? You need somethign more efficient, so another algo.