I'm back after taking a break from this game and attending to some stuff IRL. I've decided to release what I previously stated I would never tell anyone since it appears this issue is never going to get fixed.
If you want to make the aiming a bit better, make a smurf and make that your new tag for halo. Don't Open any packs that give you permanent unlocks. Eg. Emblems, Weapon skins, Armor pieces. The more you have unlocked the heavier your aim is going to get. I assume this is because every permanent item you unlock gets loaded into the ram when your player profile loads and there simply isn't enough or some other issue exists. Every time you purchase one of those new content packs, it will get worse.
Wow. Not just wow, but WOW. Makes so much sense, but here's a few reasons:
1. Explains how it seems to get worse for more people with every update as the game gets more bloated and more and more new Reqs are released.
2. Explains how some people continue to say some of these issues don't affect them. They probably don't open many packs and just play the game.
3. Explains why 343 is so silent on the issue because it will kill the micro sales.
4. Explains how you found that emptying the local cache might yield a temp improvement.
So much for lobbying for limitless customization options. I'm sure you will be challenged on this and maybe get some grief, but dude, I'd like to gift you Bunch of Req packs... ;-)