Sharepoint 2013 bad query performance

Hey there, 

we got a new SharePoint 2013 Server, it has has 8 GB RAM and 4 Cores. 

It's just a Test so there isn't much data yet, the pages load really quick too. 

But if i write a TestApplication and execute Querys their Performance is really bad. 
For Example the Execution of "CamlQuery.CreateAllItemsQuery(10)" needs 900 ms. 
There are no big Files or anything.... 

Somebody out there got some experience or at least a clue what to do?

Greetings
Ben