The Common Issues and Solutions sticky (
http://forums.androidcentral.com/lg-...solutions.html ) has a section of thread links for Touchscreen issues, including information about SGS Screen Booster.
As a side note, I'm having pretty well no touchscreen issues... but I really do think it's a matter of perspective, depending on what phone you're coming from. My old phone was a Note2 with a gazillion issues, so when I use the G4 it seems so smooth and enjoyable to use that I'm likely overlooking the occasional tap issue. The one problem I'm having with tapping is, I think, a Swiftkey issue, and I've resolved it by increasing the size of the keys.