Symbian phones like N95 does run out of power in a short-time due to simultaneous mechanisms running in the background just like those puny Windows drivers that you have no knowledge about.
I have came across some tips from gersbo.dk, of how some functions can be turned-off to minimize instantaneous battery drain.
Basic Optimizations
Update phone firmware - new firmware might include improvements to battery management.
Bluetooth - keep it off unless needed. Put bluetooth management...