Samsung working extremely slow

I unrooted my tab then did a factory reset, I then rooted my tab with Kingo Root, after rooting was successful my tab's performance became very slow. So I decided to boot into recovery mode then wipe data and cache. After that I noticed that the Samsung logo is slow. After booting my tab's performance is extremely slow, it takes time to go to the settings. So I went to look at CPU usage then I saw 98% of my RAM is being used. But the're only a few process on the list using a bit of RAM but they keep restarting. So I removed the root of my tab to see if that works, but it didn't. After rebooting my tab it says "process system isn't responding" Can anyone help me?