The two T-SQL functions, DelimitedSplit8K and DelimitedSplitN4K, that are attached to the article I referred you to are optimized to split varchar(8000) and nvarchar(4000) strings.

I would read the article and discussion again, as use these functions on appropriate sized strings to see how they work.

For string longer than varchar(8000) and nvarchar(4000) you will probably want to go to a CLR splitter as it will out perform a T-SQL based splitter.