thanks, I see the conversion but what I do not get at this point is if a conversion is made then why wouldn't a SEEK happen like if there was no N'?

As mentioned if I convert the table field to BIGINT and run the query with the N' clause a SEEK is performed, but of course it does not if the table field type is VARCHAR.

Assuming this is the case and a SCAN must be performed then the overhead from a lot of transactions is very high in extra reads and cpu time.