**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.
{
    size_t src_pos = 0;
    size_t dst_pos = 0;
    for (; dst_pos < num_bytes; ++dst_pos, src_pos += 2)
        dst[dst_pos] = unhex2(reinterpret_cast<const char *>(&src[src_pos]));
}
void parseUUID(const UInt8 * src36, UInt8 * dst16)
{
    
    parseHex(&src36[0], &dst16[0], 4);
    parseHex(&src36[9], &dst16[4], 2);
    parseHex(&src36[14], &dst16[6], 2);
    parseHex(&src36[19], &dst16[8], 2);
    parseHex(&src36[24], &dst16[10], 6);
}
void parseUUIDWithoutSeparator(const UInt8 * src36, UInt8 * dst16)
{
    
    parseHex(&src36[0], &dst16[0], 16);
}
/** Function used when byte ordering is important when parsing uuid
 *  ex: When we create an UUID type
 */
void parseUUID(const UInt8 * src36, std::reverse_iterator<UInt8 *> dst16)