[Galaxy S 5 Q&A, Help & Troubleshooting] jacobgong:
It's an LTE-A 906L variant

Obviously this isn't one of those noob questions where I would have the same ROM since the phone was new except I just have 300 more apps and 150 of them running in the back ground "slow".

It's not that, I have used multiple ROMs, now I'm on I think NOVA or whatever, one of those de-bloated official ROMs. Now days it just feels SO SLOW! And I almost don't install any apps! I have like one drawer page of apps!, the only apps I installed are 9gag facebook and wechat, I don't even install any games, everything else are just stock or Gapps. For example, if I press the recents key, it takes at least 1 sometimes 2 seconds for the recents menu to appear. and it takes about 3 seconds to launch Google Now. With the browser (chrome or stock), while scrolling doesn't lag, but switching tabs takes forever (seconds).

Also battery life seems to have gotten worse, I can always get through the day just fine, but there has been a few times I got home with 5% battery, because it's just always awake! Looking at stats from wakelock detector, the thing is awake AT LEAST 25% of the time (as much as 40%) even when just sitting there doing nothing and there's nothing I can do because the top wakelock calls coem from wechat,google, facebook messenger, email, and samsung stuff, I can't turn them off or I loose functionality. It drains ~20% overnight.

Notice how I've been saying that this is how I FEEL, because I don't really have reliable data for when the phone is new, maybe it's just in my head and it's always been like this? The only explanation I can think of is that I have since gotten myself an iPad Air 2 and it's been amazing, the battery life is just endless it feels impossible to drain even 30% while I can't see my S5 lasting more than 4 hours screen on. task switching on the iPad never takes more than 1 second, and apps seem to stay in memory for longer even though it has less memory.

I know AOSP/CM based ROMs are significantly more responsive, but I can't use them because they're not as reliable, and more importantly, I loose functionality with my Gear S2 watch.

I'm not trying to hype Apple here, I don't want to get an iPhone, if I decide to retire the S5 I'm most likely gonna get an S7. But I'm still hesitant because I saw this video on youtube with practical app launching test on the S7 and it turned out to be still WAY slower than the iPhone 6S, which makes sense. I mean yea Snapdragon 820 is fast, but single core is still not as fast as the A9, and app launching as well as most common tasks are still more single thread dependent. The 6S also has NVMe drives which again, blows away any android phone in flash performance. Some people have commented that the S7 wasn't on Wifi while the iPhone was, but I don't have either of the devices so I don't know if that makes any difference.

I really don't care about benchmark performance I just want a responsive and reliable phone. I'd have gotten an iPhone but I can't for a few specific reasons. One of them being the inability to arrange icons, because they're always in the way of my favorite wallpapers, I know it sounds silly but that's basically the reason I don't want to use an iPhone... I'd generally prefer Samsung because of the amazing screen , there should be no doubt Samsung has the best phone screens there is. iPhone is good for LCD, but cannot compete in absolute terms. So that leaves things like G5 out of the picture because the G5 is still LCD, and not even quantum dot it would seem.