Jailbreak tweaks, when written correctly, use very little ram. They use single digit kilobyte amounts each. Hardly enough to warrant a problem with the rest of the OS' ram management.
Far from all tweaks are written correctly.
Springboard itself is very good at clearing itself of unused ram and will in fact lower its overall ram usage when idle.
That's true, but no matter how good iOS is at releasing RAM - it's not gonna release allocated RAM that a tweak claims it needs, at least not without causing freezes.
Springboard respringing is not caused by low ram. It is caused by an unstable tweak. Unstable tweaks are also the reason why Springboard goes into safe mode, not low ram.
Of course excessive memory use can cause system wide instability and crashes.
iOS freezes are rarely, if ever, caused by low ram.
You do realise that the process of freeing up RAM (not just deleting the suspended state of an app) freezes the phone, right?
If the app you are currently using crashes, that is likely because it has exceeded its allocated ram usage, as set by Apple or the developer. This will happen even if there is large amounts of free ram.
I had a bunch of tweaks installed on my iPhone 5, and after about eight-nine hours of normal usage I couldn't even open memory intense apps (like Need for Speed: Most Wanted). Checking the memory allocation etc. in Instruments, I saw Springboard used between 50 and 90 % CPU (out of 400 %) and around 800 MB(!) RAM. And this RAM was not being released when trying to open apps, the only thing that happened was that the app crashed and a Low Memory Crash log was being created. Opening less memory intensive apps, like Camera, took a lot longer than normal because iOS was desperately trying to free up RAM, causing freezes.
I've uninstalled the tweaks I didn't really need, and now I have no problems what so ever. Yes, Springboard does use more memory than on an un-jailbroken device, but it doesn't cause any problems. I could post a list of the tweaks I've uninstalled if you'd like to have a list of the suspects, one or more of these tweaks are definitely badly coded...
That's because iOS was using its ram for storing things, as designed. Free ram is wasted ram. Stop thinking about ram in terms of Windows. A properly performing iOS device, one that isn't used by someone with an inaccurate bit of knowledge about what they think is best for their device, has about between 5MB and 10MB of ram free after a day of usage. This is normal because the apps are to be frozen in ram so that they are not needed to be relaunched and processed when switched back to. If you do load up a heavy games, iOS will kill off the oldest apps in memory to free up space. This process is nearly instantaneous and a much better process than worrying about how much free ram your device has. If free ram really did matter that much to a user's overall ability to use iOS, Apple would have designed iOS to making having a large amount of free ram a priority.
This is theory that is all fine and dandy when talking about a non-jailbroken device. A badly coded tweak can mean this is false though.
See, if iOS simply deletes the suspended state of apps, the process is pretty seamless, but if it has to release RAM from Springboard, it's gonna freeze up the phone. And if it can't, you'll see either a crash of the app you're trying to open followed by a Low Memory Crash log, or Springboard crashing.
This becomes pretty obvious when analysing what happens in Instruments.
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Yes, but also full of misinformation.
