you probably need to rewrite the query and remove "TOP" clause - it executed on local server, not remote, so you pulling entire resultset between boxes.

simplest way

Declare @MetricDate smalldatetime

Select @MetricDate = MAX(MetricDate) from Server1.MyDatabase.dbo.MyTable where col4 = @ZipCol AND col1 = @DOB

SELECT @DOB, col2, col3

FROM Server1.MyDatabase.dbo.MyTable

WHERE col4 = @ZipCode

AND col1 = @DOB

AND col5 = @MetricDate

best way - OPENQUERY per suggestion above

index should be by col4,col1,MetricDate - your modification misses col1