**Describe the situation**
multiIf works 10 times slower than If with single condition.

**How to reproduce**
ClickHouse version 21.10

```

SELECT count()
FROM numbers_mt(1000000000)
WHERE NOT ignore(multiIf(number = 0, NULL, toNullable(number)))

┌────count()─┐
│ 1000000000 │
└────────────┘

1 rows in set. Elapsed: 10.267 sec. Processed 1.00 billion rows, 8.00 GB (97.41 million rows/s., 779.25 MB/s.)

SELECT count()
FROM numbers_mt(1000000000)
WHERE NOT ignore(If(number = 0, NULL, toNullable(number)))

┌────count()─┐
│ 1000000000 │
└────────────┘

1 rows in set. Elapsed: 1.010 sec. Processed 1.00 billion rows, 8.00 GB (990.63 million rows/s., 7.93 GB/s.)
```

**Expected performance**
The same performance for multiIf and if.

throw Exception("Bad ORDER BY expression AST", ErrorCodes::UNKNOWN_TYPE_OF_AST_NODE);
        if (order_by_element->with_fill)
            return;
    }
    std::unordered_set<String> prev_keys;
    ASTs modified;
    modified.reserve(order_by->children.size());
    for (auto & order_by_element : order_by->children)
    {
        
        ASTPtr & name_or_function = order_by_element->children[0];
        if (name_or_function->as<ASTFunction>())
        {
            if (!prev_keys.empty())
            {
                RedundantFunctionsInOrderByVisitor::Data data{prev_keys, context};
                RedundantFunctionsInOrderByVisitor(data).visit(name_or_function);
                if (data.redundant)
                    continue;
            }
        }
        
        if (auto * identifier = name_or_function->as<ASTIdentifier>())
            prev_keys.emplace(getIdentifierName(identifier));
        modified.push_back(order_by_element);
    }
    if (modified.size() < order_by->children.size())
        order_by->children = std::move(modified);
}
void optimizeLimitBy(const ASTSelectQuery * select_query)