UI Slows down when reports are not purged form DB.
If you don't purged the reports from your database the lookup queries for the last report of a hosts start slowing down due to the way ActiveRecord queries for it:
Host.reports.last will generate the following SQL statement:
Report Load (1611.5ms) SELECT * FROM `reports` WHERE (`reports`.host_id = 19) ORDER BY reports.id DESC LIMIT 1
By changing that query to Host.find(host.id).reports.maximum('id')) we make a more efficient query improving the response.
Report Load (3.2ms) SELECT * FROM `reports` WHERE (`reports`.`id` = 85955)
fixes #186 - When reports are kept in the database and not deleted/purged the Host.reports.last query starts slowing down and the hosts index page can take minutes to load depending on the number of hosts. By changing Host.reports.last to Host.find(host.id).reports.maximum('id') we make a more efficient query to the database cutting the lookup time.