So, after you complete Chapter 1 of Jurassic Park, where you have to summon the triceratops with Ian and Alan, you can actually continue charging during the cutscene showing off the Dilophosaurus' . If you just hold X and move forward, it will continue to go, and you are able to kill two of them. It probably saves only two seconds, but it is a neat trick. If you want an example, you can see it on my run.

For those wondering it starts at 29:10 on his run