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You still have the stock kernel, and it won't allow overclocking. You will need to flash a custom ROM. There are plenty of choices out there, but be aware that flashing a new ROM is not nearly as easy as rooting an android device. I would estimate that the first time will take a you couple of hours to carefully go through the process if it is completely new to you. There is also a possibility that you can brick your device, so be certain that you accept that before you start, back up everything, and carefully read through the entire process multiple times before you start. I would check out Android Central, and look in the forums section for your device. I'm not sure which LG you have, but there are some really active LG forums, particularly for the Optimus variants, so if you happen to have one of those you really are in luck.
You have taken the first step with rooting to really discovering what is great about Android devices, assuming that you are the type of person who likes playing around to optimize your device to do exactly what you want it to do. Make it faster, remove bloatware, upgrade to a newer version of Android OS, whatever you want. It is not for everyone; one of my good friends that is mod crazy in almost every aspect of his life uses an iPhone because, as he put it, "I just want one thing that works well without me messing with it."
Again, you can brick your device, but that is pretty unlikely if you are careful and READ, READ, READ before you start. Good luck!