Do NOT use Sitecore.Data.Database constructor

How to kill your website - part x

This post could indeed also be called "How to kill your website" because that is what using the constructor of the Sitecore.Data.Database class in Sitecore will do. 

If you set your log level to INFO and see something like this in the log files:

4184 08:30:17 INFO  Cache created: 'web[blobIDs]' (max size: 500KB, running total: 624MB)

4184 08:30:17 INFO  Cache created: 'web[blobIDs]' (max size: 500KB, running total: 624MB)

4184 08:30:17 INFO  Cache created: 'web[blobIDs]' (max size: 500KB, running total: 625MB)

4184 08:30:17 INFO  Cache created: 'web[blobIDs]' (max size: 500KB, running total: 625MB)

4184 08:30:17 INFO  Cache created: 'web[blobIDs]' (max size: 500KB, running total: 626MB)

4184 08:30:17 INFO  Cache created: 'web[blobIDs]' (max size: 500KB, running total: 626MB)

4184 08:30:17 INFO  Cache created: 'web[blobIDs]' (max size: 500KB, running total: 627MB)

This means you have a memory leak...  you're site is dying. Slowly (maybe), but surely.
Look into your code and see if you have ever used new Database(). And then get rid of that code.

How to fetch a database

The wrong way:

var database = new Database("web");

The right way(s):

var database = Sitecore.Data.Database.GetDatabase("web");

or

var database = Sitecore.Configuration.Factory.GetDatabase("web")