This thread should come with a disclaimer that not all tweaks work equally on all roms/kernels and may in fact make things worse depending on rom/kernel combo.
I view build.prop and init.d scripts as experts only. Sure it's easy to copy and paste them into any rom but it takes a lot of knowledge to determine whether it's necessary.
For example, look at all the roms posted by relative noobs. They include v6, loopyblahblah and a random selection of knzos tweaks and scripts. Now take a look at the most recent rom posted by knowledgeable developer doktornotor (RIP we miss you!!) he didn't include a lot. Why, because CM7 is already extremely optimized and francos kernel is insanely optimized specifically for the 01. All the battery drain, FCs and general instability are often linked to an unneeded tweak or Pokemon theme that UOT butchered. More often than not, less is more.
If you're running a rom based on stock LG and an earlier or less modified kernel then some of the build.prop and vm tcp and other tweaks can benefit you IF you know what you're doing.
My current setup:
Rom - stripped down version of mik_os CM7 6.5.7 @ 480/768 SmartassV2
kernel - ZackS Venice 3.4 (fork of francos kernel including fserve and Paulos tweaks)
build.prop tweak
Code:
wifi.supplicant_scan_interval=120
init.d scripts - added remount and zipalign. Removed "05mountsd" since I don't have an ext partition and I removed zram.
I also added knzos gps tweaks and lowered wifi txpower to 18. I've included the patched libsqlite.so and soundfx libs
Tweaks I'm testing - microSD card speed tweak (I'm still playing with the value). I have a class 6 card and I think this is a keeper. If however I was using the included class 2 card I don't think I'd use this tweak or at least not the suggested 2048 value.
This setup has no bugs (other than those on miks known list) it's fast, smooth, stable and battery life is good. If this setup is not enough, consider buying a faster phone or getting your head checked