Improved Performance at TDF

[TDF_Management]

In an effort to improve overall performance we have reduced the online stats to reflect a 30 minute period instead of a 60 minute period.
ie.

In total there are ### users online :: ## registered, # hidden and ### guests (based on users active over the past 30 minutes)

This stats feature does utilize more resources as numbers increase, and will result in better performance during periods of higher traffic.

TDF Management