Minimizing your Script

The following is only important when a script does a CPU intensive task that is known or has been tested to affect the frame rate. This is generally reduced to situations that involve naive searching, sorting, or constant iteration through many references. Code that must have inefficient algorithms can best take advantage of the techniques here. Note that almost all code produced with the vanilla editor will already run well, regardless of programming technique.

Gamemode Scripts

Avoid using gamemode scripts wherever possible. Use quest scripts if you can, or try to find ways to put as much of the script work into OnLoad, OnEquip, and ScriptEffectStart blocks as possible.

If you need to use a GameMode block, use an 'if' test or a flag so the code will only run when necessary. For instance, if you need to run an item script whenever the player hits a switch, place this on the switch:

scn YourSwitchScript

short Working

begin onActivate
  set Working to 1
end

and this on the item:

scn YourItemScript

begin GameMode
  if YourSwitchScript.Working
...
  endif
end

An important note on If blocks vs early Returns

The Morrowind scripting community determined that the script engine would process all code inside of an If block (even if the condition was false) until the script engine could find an exit point. An exit point can be either an accessible RETURN call, or the end of the script. It appears that this is also true in Oblivion - see the OblivionScriptsOptimized thread linked below.

This:

;; unoptimized

begin GameMode
  if (some condition) != 0
    (some inefficient/complex algorithm)
  endif
end

Is considerably more expensive than this:

;; optimized

begin GameMode
  if (some condition) == 0 ;; logical negation
    RETURN
  endif

  (some inefficient/complex algorithm)
end

In short, best practices for Oblivion scripting are to call RETURN early and often. For large scripts this subtle coding difference can yield dramatic performance gains.

External thread of tips

OblivionScriptsOptimized