Is that a particularly expensive query? The total cost of all the operators in the query will be 100, so if it's a simple query, there's nothing wrong with one operator being 85% of the total cost.
Can you perhaps post the exec plan for us to take a look at?
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability