使用row_number时全文索引查询变得很慢？

Question

table1的行很大，而field1是文本，因此我创建了field1的全文索引。

我在下面运行sql，它运行非常缓慢，并且CPU一直运行到100％。

select * from (
    select *, ROW_NUMBER() OVER(Order by [createtime] DESC) AS RowId 
    from table1
    where CONTAINS(field1, 'sometext')
) AS t1
where t1.RowId between 1 and 10

我删除了RowId查询，查询速度很快，不到1秒。

select * from (
    select *, ROW_NUMBER() OVER(Order by [createtime] DESC) AS RowId 
    from table1
    where CONTAINS(field1, 'sometext')
) AS t1

然后我认为这与SQLServer优化有关，我尝试将zero添加到RowId查询字段中。

进展很快！但是为什么呢？

select * from (
    select *, ROW_NUMBER() OVER(Order by [createtime] DESC) AS RowId 
    from table1
    where CONTAINS(field1, 'sometext')
) AS t1
where t1.RowId + 0 between 1 and 10