Thanks for the suggestions regarding the use of ZRAM.
First of all this is not a new feature in the kernel as the stock kernel makes use of it too. Whats new is that the drivers are updated and the LZ4 algorithm is used for compression/decompression instead of LZO.
Why do we need ZRAM?
Simply we do not have that much RAM and swapping to disk is slow.
When the device is going out of RAM the ZRAM expands the amount of available RAM by compressing unused data in the RAM itself. This benefits in avoiding slow I/O processes caused by swapping to disk. LZ4 is a very fast compression algorithm with up to 3 times faster decompression than LZO. Of course this doesnt come out of nowhere and some cpu cycles must be used for compression and decompression. But after all i would say it is worth the price for a bit of snappier performance.
How much RAM does the ZRAM use?
Only the amount of compressed data is used from available RAM. So when there is no data compressed in ZRAM the device can make use of the full inbuilt RAM.
Does deactivating ZRAM increase RAM?
...I'll stick with it for now. Time will proof.
If you really want to deactivate maybe ask @holymoz
he can guide you.