codeigniter load slowly on refresh

[eluser]Unknown[/eluser]
Hello

I have used codeigniter on ubunto and windows and never had the following problem. I set it up on a mac osx and first loading takes time and then the pages loads fast and after a while like 30 sec with no activity the refresh take 5sec .

i am using database session

What this problem can be related too ?
No solution in any of the posts ?