How slow is slow in postgres?
You have to first set expectations - a screen that does such and such activities should complete each action in 1 second and all actions in 5 seconds and so on. For example, a search screen should retrieve results in 3 seconds, the booking actions (ticket booking) should be completed in 30 seconds etc. 

Then work towards meeting those targets. That is the "normal" performance you want. Now go about meeting those targets. The database may be your bottleneck, it may not be. To identify issues at the database side, try using a tool like pgbadger. That will tell you which queries are taking time. 

By the way, 8 hours for a query is probably not acceptable under any circumstance. Try the tool pgtune and see if there is scope for optimizing parameters.