[LUA] Best way to track an object's location?

I've got a series of scripts for spell effects generated by the characters of my D&D group, but they all hinge off of a few lines of script that constantly track the locations of their character objects.

Those lines are:

```function onUpdate()```

``` if mainPC ~= nil then```

``` pos_PC = mainPC.getPosition()```

``` rot_PC = mainPC.getRotation()```

``` end```

```end```

Now as I'm sure you can guess, the problem is with onUpdate lagging everything to shit, especially when the function is duplicated across six different player effects trackers, a time of day tracker, and some other things I'm sure I'm forgetting.

There has to be a better way of doing this. Any ideas?