SQL Server performing slow
Following discussions in chat, we've established:


32bit Enterprise SQL Server.
3.5GB of memory in use (no AWE/PAE).
2.1GB database with 1.3GB buffer pool.
Page life expectancy of 3 seconds.


Suggested fixes are:


AWE/PAE as a quick fix so the database fits in memory.
Investigate the frequently called, highest IO queries identified.
Consider rebuild to 64bit.