Is there is any Performance issue while using ISNULL() in SQL Server?

Question

I am using ISNULL in MS SQl server 2008, since my table is too huge, whether using of ISNULL may cause any thing to the performance ?.

Than

Answer 1

Yes it can. For optimizer is better rewrite the query (if possible) to form

(Field = @x OR @x IS NULL)

Because using functions in certain cases prevents from optimizer to use statistics and sometimes forced implicit datatype conversions