@Erikur, Sorry, I forgot to ask- is parallel execution worse, how to avoid parallel execution
As Frederico stated, it is neither better nor worse, it depends. For high cardinality sets with a sorted output, parallelism is normally worse, but this is a thing that has to be tested.
To prevent parallel execution, simply add "OPTION (MAXDOP 1)" at the end of the query.
Can you elaborate further and post the full code as previously requested?