New ASUS A455LN run so slow and super lag even with browser

[tffanylim]

I just bought my ASUS A455L like 2 months ago and I just realized it become super slow and lag. at first it did not show any problem (lag or slow), it run so well. I had it reboot like twice, but I'm not actually get through the menu. SO I just press the reboot key without getting on the menu. Is my laptop become so slow because I did it? Anyone know how to solve this problem, please tell me how to solve it step by step. I don't really understand about devices like this, but I can do it if you give me some tips with steps. This is just too annoying for me, because my old laptop (ACER i3) never get this lag before.

Here's my spec: ASUS A455LN, i5, NVIDIA GEFORCE 840M, RAM 4GB, HDD 1TB, WIN 8.1 64bit

your help will be much appreciated!!

 

[tffanylim]

And some addition, my hard drive is still so empty. I only touch less than 200GB.

 

[Kenzo_1]

Have you tried optimisation app like ccleaner?

 

[velo3100]

What background processes do you have?