def is_slow_wpt_test(self, test_name):
        # When DCHECK is enabled, idlharness tests run 5-6x slower due to the
        # amount of JavaScript they use (most web_tests run very little JS).
        # This causes flaky timeouts for a lot of them, as a 0.5-1s test becomes
        # close to the default 6s timeout.
        if (self.is_wpt_idlharness_test(test_name)
                and self._build_has_dcheck_always_on()):
            return True

        match = self.WPT_REGEX.match(test_name)
        if not match:
            return False
        wpt_path = match.group(1)
        path_in_wpt = match.group(2)
        return self.wpt_manifest(wpt_path).is_slow_test(path_in_wpt)