How much difference in RAM usage between 720p & 1080p display? Z5c RAM way too low? - Xperia Z5 Compact Q&A, Help & Troubleshooting

How much difference in RAM usage between 720p & 1080p display? Z5c RAM way too low?
I've read several times, that a 720p display uses less RAM than a 1080p, plus the Z5c has a couple of extra features, like 500MB of ZRAM, which should make multitasking quite good and not a thing to worry about, despite the low RAM.
But here's the thing: Can anybody tell me, how much exactly is the difference in RAM usage between 720p and 1080p? I was never able to find hard numbers. Is it 50% because of half the resolution? Is it like 5% only or something else? Or is it flexible, depending on the apps? Or, if it's a fixed amount of megabytes, how much is it?
I'd love to get the Z5c due to the smaller size and it is about 100€ less than the Z5, but I'm also a heavy user and struggling very much with only 2GB of RAM in my current Z1.
I have at least 10 different apps running in the background all the time, like weather widget, several messengers, xposed, data counter, greenify, etc.
Plus, I usually like to open a lot of tabs in the browser, 10+ is quite often and my browser either craps out completely and closes itself or the tabs have to reload all the time, this even happens with only 2-3 tabs.
Same with apps.
They are almost always reloading, most of the time I can't even visit my "friends" in Simpsons Tapped out because the game crashes when I try to visit their cities or it crashes in my own town because it is too large.
The music player stops working during browsing or one of my running apps closes itself due to lack of RAM.
Is this normal, is the RAM really too low or am I just expecting too much from smartphones? I treat them like small computers, like the ads suggests. I guess, they are just too unrealistic.
The ONLY thing keeping me from going for the Z5c is the low RAM and this would be the only reason for the Z5.
Also, 2GB RAM is a 2012 standard, it's now 3 years old. After a usual usage time frame of the Z5c of 2 years, it's 5 years behind. I simply can't seem to get myself to buy an already outdated device in terms of RAM. For me, 4GB would be very welcomed.
Can anybody answer my questions regarding RAM usage or someone with a similar heavy use case can relate their experiences with the Z5c and RAM problems?

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The RAM is more than sufficient. I have been using this phone for some time now and I can keep any number of apps open in the background and they do not close.
---------- Post added at 05:38 PM ---------- Previous post was at 05:37 PM ----------
When I say "any number" I mean any number of apps that I need to keep running in the background. I've never run out of RAM on this phone. Whereas I see a lot of phones struggling with multitasking

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I don't just mean many many foreground apps which I have started myself and switching between them, but also like 10+ apps which are running as soon as the phone has finished booting and which I want to run in the background all the time, without counting additional apps which I open on purpose. Apps always running are: Hangouts, facebook messenger, Whatsapp, weather widget, one handed mode, 3G Watchdog, onavo extend, proximity screen off, greenify, setcpu, automate it, afwall+, twilight. A total of 13 background apps plus many foreground apps. After everything has loaded after boot, I'm already down to 700MB free RAM, without any other open apps.
When RAM reaches 500 or below, the force closure starts.
How much is your available RAM after boot and with many apps running?

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i don't know if you are aware of it, but xposed module "app settings" has an option to keep chosen apps persistent in memory. I cannot assure it works, but probably it does. You could enable it on the apps you need to be kept open and then fill your memory fully, then see if Android system kills other apps (camera, gallery,...) instead of your favourite ones. This might be a workaround for you, or might not: if you open lots of tabs on your browser, Android kills other apps, while Windows would become sluggish but keep everything open and use the swap file. Regarding the swap theme, Android has the Zram function, a kind of swap file in the ram, that compresses some RAM in the RAM itself (at the cost of some CPU power). This might also be useful but don't know if it is already supported by stock xperia firmware or it must be implemented in a custom kernel.

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Well, available RAM really doesn't matter much. Lollipop especially is designed to take up as much RAM as possible. That makes the operations smooth and the processes run in the background. But I'll attach this here. I never clear the tasks and I always keep them running so I will have less RAM. But my apps don't close on me though

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It seems 2GB ram doing fine on my Z5c, I guess because of it comes with ZRAM enabled in stock kernel(for the cost of cpu and battery). Yes, 720P spend much smaller amount of memory and cpu compared to FHD/2K. There are many reports confirmed on Z1/Z2/Z3/S6 board when people used resolution changer and found much more free ram available, you can try QHD 960x540 if you want even more free ram.
I got 1GB free ram after boot up and same with my S6 but since my S6 running 2K resolution with poor Samsung memory management, actually the Z5c performs better when deal with the killing apps problem. If you will use greenify donate ver to freeze all bloatware I think memory is good, the android 6.0 seems to have better memory and battery life as well.

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Can you tell me more about the resolution changer? Is it dangerous and can lead to a bootloop or not booting at all?

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Z have 2gb of ram and 1080p display and have no ram issue..

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drsoran2 said:
Can you tell me more about the resolution changer? Is it dangerous and can lead to a bootloop or not booting at all?
Click to expand...
Click to collapse
http://forum.xda-developers.com/galaxy-s6/general/how-to-run-s6-1080-mode-t3124559
I don't use it on my S6. It won't bootloop or not booting but just some stock apps will have menu problem bcoz they are hard coded for native resolution, you may need to decompile those apks and edit some .xml files manually to modify the default resolution to make it works.

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even my XZU with 2GB of RAM and 1080FHD is still perfectly able to multitask. no need to panic for such 2GB of RAM. yet. :fingers-crossed: well maybe when there's a game with big memory requirement in 2-3years time then you'll need more than 2GB but i bet it's not a game worth playing coz it's not mobile optimized and the devs are too lazy to optimize.

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Default set at 507MB ZRAM, you can increase it to 1024MB if you wish

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Yes, but only with root? And then you lose the warranty, camera functions, miracast and such because you need to unlock the bootloader.
A root exploit without bl unlock, like on my Z1, is what I'm hoping for. I also don't understand why manufacturers don't implement to gain root access via a simple reboot. Make the option available, display maybe 2-3 warnings and info screens before, then if you click yes, a reboot happens and you're rooted. Easy as this. No features lost, no exploits necessary which take forever to arrive, if at all, and involve downgrading and such. I think one manufacturer enables exactly this.
It would be unthinkable on a Windows or Linux system if there wouldn't be the option to work with full admin rights...so why is it the norm on Android and nobody bats an eye?!
Btw: I've tried the resolution changer and changed the resolution to 720p. Although this should have decreased the RAM usage, it actually increased it by around 100MB. How is that even possible?

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drsoran2 said:
I'd love to get the Z5c due to the smaller size and it is about 100€ less than the Z5, but I'm also a heavy user and struggling very much with only 2GB of RAM in my current Z1.
Click to expand...
Click to collapse
I think you answered your own question here. If you need a whole lot of RAM, you should probably look somewhere else.

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yes, it needs root and you loss warranty and DRM and such stuffs.
Linux like to cache things, if u got more free ram it might just cached even more. It won't used more 100MB ram in reality.

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The thing here is the Android 64-bits.
1080p device with 2GB RAM in Lollipop 32 bit = more than 1000MB of free RAM (average).
720p device with 2GB RAM (and zRAM) in Lollipop 64 bit = more than 550MB of free RAM (average).
Now, the resolution mostly affect the used RAM when gaming, there is not a big difference outside games.
Sent from my E5823

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thesebastian said:
The thing here is the Android 64-bits.
1080p device with 2GB RAM in Lollipop 32 bit = more than 1000MB of free RAM (average).
720p device with 2GB RAM (and zRAM) in Lollipop 64 bit = more than 550MB of free RAM (average).
Now, the resolution mostly affect the used RAM when gaming, there is not a big difference outside games.
Sent from my E5823
Click to expand...
Click to collapse
I have never seen free memory more than 1GB of RAM with my XZU. Right now it hovers around 600MB of RAM.
for gaming it is not an 'always' case so memory cleaning at the end should happened only 1% of the time you use the phone.

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Who cares about how much free ram there is? The ram is meant to be used and Android is made to use the RAM for caching and so on.
Talk instead about how well it runs in practice.
Anyone that has experienced any problems that could be because of the device only having 2GB of ram? Let us know.
If not, then I guess the fact that the Z5C "only" have 2GB ram is not a problem...(?)

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Here,me! I'm having a lot of problems because of low RAM and the whole purpose of this thread is to find out if the Z5c with its 720p display and zram and such makes a huge difference in RAM performance, if at all compared to my Z1 with also 2GB which is always reloading tabs, crashing games and apps, force closing apps due to lack of RAM, redrawing the home screen when exiting apps and so on.
If there's no big difference, then devices with only 2GB are not for me.
It's good that Android uses all the RAM for caching, but I strongly believe that in my case there is simply not enough RAM and that's why all my problems occur.

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And also Z5c uses LPDDR4 RAM if I am not mistaken. So that's actually more efficient. Well I have faced ZERO problems with multitasking. But I dunno about you