About a year ago I've created a SharePoint application which used document library as it's main storage. I knew that there are some limitations and restrictions but after reading the following article:
Manage lists and libraries with many items I thought that it's not a problem if you setup the indexed columns and views properly.
However, once the library has reached 6000 plus something items, everything suddenly slowed down dramatically, basic queries which used to load in 1 second started to time-out or take more than 60 seconds to load.
In addition to that,
WorkflowServiceHealth.aspx page just died and only returned "Timeout Expired" error.
