Hi I hope you have solved the issue by now but in case you haven't here is my answer.
Most common issues regarding the slowness of pages due to SQL server. Recently we experienced a big performance hit, at the end we came to know query against all doc table taking 9 sec to execute. Behind the scene something trigering from SharePoint and required new stats on AllDOc
tables....MSFT still working on it to fix the issue.
Here what we did to identify the issue:
1) enable the Developer Dash Board (very safe and only site collection admin can see it), Once page loaded we check the stats at the end page and we come to know which thing required more time...you will get info i.e webpart, query, custom solution etc.
2) enable the performance counters and check it
3) use fiddler, sometimes it's really helpful.
8Gb size of Content DB is nothing for SharePoint, we have more than 10TB of data.
Also check if your list items are more than your threshold value.
For more help I found the links below helpful.