Finally I re-configured Android's built-in lowmemorykiller feature with a init.d script and totally fixed all slowdown issues on CM11. The script is same as Samsung Galaxy Note (N7000) variant which has same RAM memory (1gig) with our goody Ara.
I tested it nearly 48 hours without any reboot and finally we have a superb cm11 rom without any slowdown, lag etc... issues.
Please test and write your opinions below, thanks :)
How to install:
Download and extract zip file. This is not a flashable zip. You should copy "99lowmemorykiller" file to "system/etc/init.d/ folder and set its permission 755 via a file explorer for example X-plore or CM's default file manager.
Finally reboot the device.
Please dont mirror any file, thanks.