Here is what the author says (this is in the text file I included)
Tip: For the highest possible burst rate (photos per second),
* Disable RAW.
* Use a fast shutter speed (Tv).
* Do not use ISO 200 or higher (camera will spend time applying
some noise reduction filtering).
* Use a sufficiently fast SD card and keep it defragmented by
full erase as often as you find convenient.
* Enable the digital telephoto feature and choose the one and only
JPEG image size for which the camera doesn't need to resize
the photo (for a570is 1,9x digital telephoto this means 1600x1200).
At least on the a570is the digital telephoto feature is marked
with a "T" symbol on the LCD, and the optimum JPEG resolution
can be found by decreasing JPEG resolution setting until the "T" symbol
is no longer blue. Note that reducing JPEG resolution further (or
without the digital telephoto feature) will slow down the burst
because the camera will have to resize the image (unless your SD card
is very slow). Your camera may not have this feature.
He also says
This script is ment to shoot quickly after something moves on the LCD.
If you also want the script to be detecting motion again as soon as possible
after taking a shot, you should:
- use manual exposure (camera in M mode), must be set before running the
script
- use manual focus, must be set before running the script
- set trigger delay to the minimum allowable in your camera in your
shooting conditions (possibly 0)
- set burst/review time = 0 unless you want several images in
continous shooting drive mode
- disable shot review from Canon's menus
- disable noise reduction in CHDK RAW menu (if using long exposures)
- disable RAW saving
- use a fast, defragmented memory card
It appears that parameter g has something to do with burst mode but I'm not sure what value it requires. In the one tip section he says not to set the burst/review time = 0 if you are wanting several images in continuous drive mode. So I would try setting it to 1 and test it out, then set it to 2 and see what happens.
Obviously you'll want the trip delay set as low as possible, however too low may cause it just start triggering as soon as the script starts which is no good. Also when looking through the code that if parameter O is set to zero (fast mode, which is default) it will automatically behave as if parameter G was set to 1 initially. I don't know what that means.
It has been quite a while since I've played around with any coding in CHDK and even then it was fairly simple stuff, however looking at the script it appears to still be using the "press "shoot_half" command which is what trips the AE and AF, if you already have it pre exposed and pre focused there may be away to avoid this. I could be wrong though, as I said it has been awhile. If you're feeling brave enough you can try editing the script to remove the shoot_half commands and the sleep1000 in the fast_video_md routine. It shouldn't hurt your camera but I don't take responsibility if it does