Are you using parameterized views? You should add indexes for the parameters also. For example...

CREATE SQL VIEW v_Junk as ;
select * from bigtable ;
where somefield = ?lcParameter

use v_Junk NODATA

lcParameter = "findthis"

=requery("v_Junk")

If bigtable.dbf has an INDEX ON SOMEFIELD TAG sometag, this query should be as fast as if you did this...

USE bigtable
SET FILTER TO somefield = "findthis"
BROWSE

HTH