Why is my Xperia SP slow as hell ?

[AC Question]

I own a Xperia SP which I bought 1 year ago, it takes 5-6 seconds to open apps like Chrome,Facebook, UC Browser etc. The keypad comes up 6-7 seconds after I tap the screen.(In the best case scenario) I installed Cyanogenmod recently but the situation hasn't improved.

It's rooted and I use Greenify. It improves the condition a bit but not by much.
I've used other phones with 1 GB RAM but they aren't so slow.

Don't ask me the 'bout the worst case. (Even the app drawer takes 8 seconds to launch). I don't use many apps (7)

 

[B. Diddy]

Welcome to Android Central! Is there an SD card inserted? If so, try unmounting the card and removing it, in case the card is faulty and slowing things down.

 

[Hasibuzzaman Tonmoy]

I recently started using an SD Card but the problem has been occurring before this.

 

[Cam Leviticus Gb]

My 5yr old Xperia Ion LTEi28 with 1gb internal and 1 gb sd, got laggy when free ram went below 400mbs in the settings-apps-downloaded list. Use Cleanmaster to move what's movable. Set Googleplaystore app to not auto-update apps. Lag returned mth ago from FB mobile app updates. Disabled it and Messenger. Just use Chrome browser for those. Works fast again. Watch number of background apps.