The Users and Groups datagrids both had extra queries conducted per-row,

some due to columns and some due to URL generation.
The Users datagrid was fetching associated review request counts

per-row. The Groups datagrid was fetching Local Sites (when applicable),

associated review request counts, and associated membership counts.
We now use a combination of column-specific and datagrid-specific

query augmentation to select-related or prefetch-related the queries we

need.
The Users datagrid tests have also been updated to ensure all profiles

are pre-created for the tests. This avoids an INSERT for each missing

profile. That may occur in the real world still, when importing users

who haven't logged in yet, but only the first time the profile is

accessed, so it's not worth optimizing around that.

Unit tests pass.
Tested the datagrids manually, making sure all columns and links still

work.