Here is a list of the particularly useful debug settings of Second Life Viewer (I use firestorm, settings may not be available in all viewers)
Specifies the maximum time in seconds to wait before updating your appearance during appearance mode.
Specifies the maximum time in seconds to wait before sending your baked textures for avatar appearance. Set 0 to disable and wait until all baked textures are at highest resolution.
Maximum number of inventory items to match against search filter every frame (lower to increase frame rate while searching, higher to improve search speed.
The tag color you wish to have
(It’s more precise than the menu)
Exit mouselook when regaining focus
(Should help you taking pictures with an alt ;) )
Determines which metric units are used: 1(TRUE) for meter and 0(FALSE) for foot.
Double resolution of snapshot from current window resolution
Max number of simultaneous textures to request when using HTTP texture fetch. Changing this setting above 8 will most likely cause texture loading problems, setting above 32 *WILL* cause loading failures.
Maximum allowable downstream bandwidth for asset transfers (bits per second)
More coming soon…