In the case where one of your joins in a lookup field is based on a custom field with a transform (e.g. set the field to fixed value), DH in the background will join the R table to the Transform view. We have run into some performance issues with this.
It would be handy to have an option to have Field transforms (at least standard transforms such as fixed value, date-only, reverse sign etc...) immediately done on the raw table before the lookups (joins) are launched.
So as one of the first steps in the stored procedures rather than the T views.
Or alternatively perform them during the INSERT into the raw table as inserting with TABLOCK is not that much slower than BULK INSERT.