[Galaxy Note GT-N7000 General] WereCatf:
Having multiple apps running slows the device down because they use CPU. Having multiple apps open, but not running does not affect the system.

Yes, but the difference can be measured in nanoseconds, not even milliseconds. Let's take a very much simplified thought-excercise here:

Googling around reveals us that the Galaxy Note sports 1GB LPDDR2 memory. The speed isn't nowhere to be found, but so far I haven't seen a single mobile device with LPDDR2 have anything else than 1066Mhz memory, so I assume Galaxy Note belongs in that category, too. If one was writing 32bit double-words in memory at the maximum 1066Mhz speed that would translate into rougly 4TB/s.

The CPU can write a 32bit dword, ie. 4 bytes, per clock-cycle and running at 1.4Ghz that again would translate to 5.6TB/s.

There are several other hardware factors to play around with here, but neither the CPU or the LPDDR2 clearly is the bottleneck.

Now, on the software side of things, not all memory actually needs to be zeroed because the application code overwrites what was there before anyways when loaded, leaving only the data areas to be zeroed. Naively assuming an application consumed, say, 50MB memory for its data the whole data area could be cleared in 50MB -> 0.0000476837158203125TB / 4TBps ~= 0.000011920928955078125 seconds.

In addition to the ~0.000012 seconds it takes to clear that memory the OS needs to update its own data structures, like e.g. page tables and malloc tables, to reflect the new memory allocations. This adds another 0.000001 seconds to the time we deducted, leaving us at ~0.000013 consumed.

However, do you notice something? I'll give you a few seconds to think about it.

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Yes, that's right: these things happen anyways every single time you launch an application, regardless of how much free RAM there is before-hand. None of these things correlate with the amount of free memory and as such the amount of free RAM actually does have no bearing on memory allocation speed whatsoever.

It would be a different matter if there was less RAM available than the application you're trying to run requires: the system would have to kill one of the already-loaded applications to make room for the new one. That is, however, again a very fast thing to do; just erase all references to the application from kernel structures, including allocation table - references, mark the pages as free, and continue as normal. Bear in mind, though, that this would mean you have like 1MB RAM free, something that is not all that easy to accomplish with the automatic memory-management of Android!

Or to put all this into much shorter, more friendly terms: you're talking out of your ass.

Given the Galaxy Note's size-constraints it is most likely a POP-package mounted on top of the CPU, not individual chips on the motherboard. Also, as long as the memory is powered-on they do not consume any more power when there's something in them as compared to when there is nothing in them; the chips do not know and do not care what type of content they hold, all the care about is 'on' and 'off.'

Besides, LPDDR becomes only warm, not hot. You can perfectly well put a finger on the chip and not burn yourself.

Also, you've got your reason->consequence - sequence wrong here. Something becomes warm because it consumes more power, not the way you claim that it consumes more power because it gets warm. The warmth is a byproduct of it consuming power.

As such you're again completely out-of-the-woods here.

---------- Post added at 02:13 AM ---------- Previous post was at 02:12 AM ----------

Android has a habit of doing that even when there's plenty of free RAM to go.