Question: Is there any open source findbugs detectors extensions, espcially for performance bugs, for low-latency? I didn't find any meaningful extension beyond barebone findbugs impl.

Answer: 
The database file you add to the project will be embedded in the main `NSBundle` (see `[NSBundle mainBundle]`).

In order to do what you want, you need to copy the database from the main bundle to the documents folder before trying to access it. Otherwise, as you are experiencing, you will not be able to find the SQLite DB on the document's folder.
You can copy your database, click finder and write this address(/Users/administrator/Library/Application Support/iPhone Simulator/6.1/Applications/) in finder click ok.
You will get documentary path. 
Open your project document file and paste your database....