What is the underlying table clustered on? If it's clus on identity, you should seriously consider clustering instead by date first, esp. if you (almost) always look up by date, rather than ident. You can add the ident to the end of the clus key to guarantee a unique key.
That will reduce the time as much as possible across all queries when coming specifying a date.
SQL DBA,SQL Server MVP(07, 08, 09) Prosecutor James Blackburn, in closing argument in the Fatal Vision murders trial:
If in the future, you should cry a tear, cry one for them [the murder victims]. If in the future, you should say a prayer, say one for them. And if in the future, you should light a candle, light one for them.