**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.

{
    if (!select_query->groupBy())
        return;
    const auto & group_by_keys = select_query->groupBy()->children;
    GroupByKeysInfo group_by_keys_data = getGroupByKeysInfo(group_by_keys);
    SelectAggregateFunctionOfGroupByKeysVisitor::Data visitor_data{group_by_keys_data.key_names};
    SelectAggregateFunctionOfGroupByKeysVisitor(visitor_data).visit(node);
}
void optimizeDuplicatesInOrderBy(const ASTSelectQuery * select_query)
{
    if (!select_query->orderBy())
        return;
    
    using NameAndLocale = std::pair<String, String>;
    std::set<NameAndLocale> elems_set;
    ASTs & elems = select_query->orderBy()->children;
    ASTs unique_elems;
    unique_elems.reserve(elems.size());
    for (const auto & elem : elems)
    {
        String name = elem->children.front()->getColumnName();
        const auto & order_by_elem = elem->as<ASTOrderByElement &>();
        if (order_by_elem.with_fill 
            || elems_set.emplace(name, order_by_elem.collation ? order_by_elem.collation->getColumnName() : "").second)
            unique_elems.emplace_back(elem);
    }
    if (unique_elems.size() < elems.size())
        elems = std::move(unique_elems);
}
void optimizeDuplicateOrderBy(ASTPtr & query, ContextPtr context)