**Describe the situation**
https://markify.dev/p/zfrQMV2/text

**How to reproduce**
On aws `c5ad.24xlarge` run a query:

```
SET max_memory_usage = '100G', max_threads = 1000, max_insert_threads = 96

INSERT INTO wikistat WITH
    parseDateTimeBestEffort(extract(toLowCardinality(_path), 'pageviews-([\\d\\-]+)\\.gz$')) AS time,
    splitByChar(' ', line) AS values,
    splitByChar('.', values[1]) AS projects
SELECT
    time,
    projects[1] AS project,
    projects[2] AS subproject,
    values[2] AS path,
    CAST(values[3], 'UInt64') AS hits
FROM s3('https://....s3.eu-central-1.amazonaws.com/wikistat/original/*.gz', '...', '...', LineAsString, auto)
WHERE length(values) >= 3
```

Performance is not bad (22 million rows are inserted per second) but can be better.
UInt16 second_code_point = unhex4(second_hex_code);
                    if (second_code_point >= 0xDC00 && second_code_point <= 0xDFFF)
                    {
                        UInt32 full_code_point = 0x10000 + (code_point - 0xD800) * 1024 + (second_code_point - 0xDC00);
                        s.push_back(((full_code_point >> 18) & 0x07) | 0xF0);
                        s.push_back(((full_code_point >> 12) & 0x3F) | 0x80);
                        s.push_back(((full_code_point >> 6) & 0x3F) | 0x80);
                        s.push_back((full_code_point & 0x3F) | 0x80);
                    }
                    else
                        return error("Incorrect surrogate pair of unicode escape sequences in JSON", ErrorCodes::CANNOT_PARSE_ESCAPE_SEQUENCE);
                }
                else
                {
                    s.push_back(((code_point >> 12) & 0x0F) | 0xE0);
                    s.push_back(((code_point >> 6) & 0x3F) | 0x80);
                    s.push_back((code_point & 0x3F) | 0x80);
                }
            }
            return ReturnType(true);
        }
        default:
            s.push_back(*buf.position());
            break;
    }
    ++buf.position();
    return ReturnType(true);
}
template <typename Vector>
void readEscapedStringInto(Vector & s, ReadBuffer & buf)