[Sprint Samsung Galaxy S III] JakeG1984:
To give back to the community in some way I'm posting my setup. It's been almost flawless but a few tweaks were needed after flashing.

(I just realized a new build was release here since I last visited of which I haven't tried so my comments about using 4-10 build are in that context)

I've settled on only using the 4-10 build for the d2spr and have installed it on 3 separate devices with repeatable results all of which are daily drivers. When I tried the later builds I encountered issues.

Despite the things below I have my s3 pretty loaded down with apps that I use every day.

Heavy camera usage (with flash and rotation etc..) has caused reboots for me but the camera always works again after reboot.

Setup-

Build: 4-10 from this thread

Recovery: TWRP 3.1.1

Gapps: can't remember! (I think I used gapps pico dated near 4-10 but it doesn't look like you can grab that old of versions anymore)

Change-of-ginzo.zip for APN settings

Root: Magisk-v17.1.zip

Kernel auditor from play store (use for build prop edits)

What works for me:

GPS, Bluetooth audio, WiFi, VoIP calls, camera (front and rear but not video conferencing), calls, SMS, MMS (unreal mobile), full day of battery most days, root with magisk, kernel adjustments with kernel auditor, app switching and phone answering is fast almost every time for me!

Settings to change:

I mostly use lowest brightness with auto adjust turned on

I disable allow background for all apps that I don't need to run in the background. Don't disable background running for any app that you need notifications for.

To disable background running: settings/privacy/privacy guard/three dots/advanced. Then scroll to the right to the 'Background' tab where you'll see everything that's run in the background and when. Just tap the app and toggle off background running.

I disable start at boot for any app I don't need to run at start up (do this from the same setting screen as above just go to the startup tab)

I disable NFC in settings

For mic issues with WiFi calling I change too 'false' the two build prop settings that contain voip in the name (do this with kernel auditor).

I use Link2SD app to freeze or uninstall system apps I don't need or use like email, exchange services, and NFC service.

I use darks themes in apps wherever available.

Lite apps for reduced ram:

I use an old Google app (9.5.5.2.1) found from unofficial sources. Voice searches are fast and voice input from keyboard is fast. The newest google app dogs the s3 down big time!

If you use any old version of apps you must disable automatic updates!

Outlook was a heavy app for me and wasn't allowed with rooted device so I used gmail's built in outlook support for my work email. It works really well and has no problem with root!

I use Google Maps Go and Navigation Go

I use trebuchet launcher (default for this build) it kicks everything else's butt for ram usage.

I use YouTube Go downloaded from unofficial sources

I use Facebook lite and messenger lite - so much better than standard app and uses way less ram (be carefully with long posts as sometimes the screen refreshes and u can lose your text)

I use yuzu browser because it has tons of features like inverted render mode and is light on ram (but it doesn't allow password saving) so I still have chrome installed

Chrome has to be installed for maps go to work but I turn 'allow background running' off for both browsers and Maps Go Navigation still works with screen off - I think)

I'm out of time now so I'm just going to post this. Change of jinzo.zip apn info can be found on earlier posts in this thread (I think). I will add to this post as I think of more stuff.