**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.
{
    assert(current >= in.position());
    assert(current <= in.buffer().end());
    const size_t old_bytes = memory.size();
    const size_t additional_bytes = current - in.position();
    const size_t new_bytes = old_bytes + additional_bytes;
    
    
    if (new_bytes == 0)
        return;
    assert(in.position() + additional_bytes <= in.buffer().end());
    memory.resize(new_bytes);
    memcpy(memory.data() + old_bytes, in.position(), additional_bytes);
    in.position() = current;
}
bool loadAtPosition(ReadBuffer & in, Memory<> & memory, char * & current)
{
    assert(current <= in.buffer().end());
    if (current < in.buffer().end())
        return true;
    saveUpToPosition(in, memory, current);
    bool loaded_more = !in.eof();
    
    
    assert(in.position() >= in.buffer().begin());
    assert(in.position() <= in.buffer().end());
    current = in.position();
    return loaded_more;
}
static void findAndSkipNextDelimiter(PeekableReadBuffer & buf, const String & delimiter)