Slow starting window on inspiron 15-5559

I have just bought a Dell Inspiron 15-5559 with intel i5 and upgraded to 8GB ... But I found that it take around 1 and half minutes to start the window (window 8.1) before I installing any program (still factory mode)

So, I send to the nearby computer shop, they told me that need to be format. But after I get back my laptop, it still giving the same result.

This is the first time I use dell, so wanna to know is this the normal speed for starting window? because I feel it is a bit slow compare to my previous laptop