I'll basically echo what everyone else has said, but here's the ideal settings for greatest performance (no noticeable lag and yet supreme battery life) for your CPU on a (preferably free) CPU Tuner app. Note that this is AFTER installing giantpune's custom kernel appropriate, and most up to date, for your version of the Optimus Elite:
Min: 245 MHz
Max: 1612 MHz
Governor: smartassV2
Now, as for the rest of speediness, any custom ROM will do - Aeneas, Chaos, Project Mayhem, Harmonia, ICS Optimus Elite Aeneas Build all will yield to you improved speed over the stock/vanilla/came-with-the-phone/pre-installed ROM. While Tagged and Sleipnir are reportedly the two fastest/most efficient for the Optimus Elite. After installing CWM, and giantpune's kernel (note that it is installed by default in Tagged and Sleipnir), feel free (and it is highly recommended) to install one of the many custom ROMs available. And enjoy your reborn OE while you're at it.