Smile super lagging

Greetings friends
I m finding a way to overcome the problem that I m facing with my note 3.
The note 3 is now already 10+ months old.
Since February, the note 3 have started to lag abit. But now it's even worse.

WhatsApp had to be opened in order for the message to load. And even typing on website have become laggy.
Connecting to wifi so slower

I have reset my phone 3 times. And I don't think I want to do it again. Cause my message are all gone and some data is loss.

Is there any other suggested way?

Thank you.
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