You can use the optional INLINE LENGTH specification to specify the inline storage size. When the data is smaller than or equal to the inline storage size, it is stored inside the base row. Otherwise, the data is stored as a LOB (large object).
If the inline length is equal to the maximum length specified for the data type, the data type is treated as a nonLOB type. In this case, the performance may be better because there is no LOB overhead. You may see some performance improvement especially when the data type is used with UDFs.
You can choose a larger inline storage size when most of the table scans are on the XML column, therefore avoiding LOB table access which slows down performance.
Alternatively, you can choose a smaller inline storage size when the XML column is accessed only in a few of the table scans. This reduces the row size of the base table row which may improve table scan performance.