How to fix bad Wi-Fi after updating ios 7?

I recently updated my iphone to ios 7 and the Wi-Fi became SUPER slow. Do you guys know any solutions possible?
(its not the Wi-Fi itself that is slow because it is really fast on my laptop)

Is it possible to go back to iOS6 from iOS7 in iPhone 4?

I got an iphone 4 and updated it to iOS 7… The OS was laggy but i thought the next update will fix it… But i checked my friend's iphone 4s and found it to be as smooth as ios 6… I figured it's a problem with my hardware so it's never gonna get fixed… Is there a way to downgrade to ios 6?
why update the iph 4 if the hardware couldn't handle it? I'm disappointed with apple… They probably did this intentionally to force users to upgrade…
now my iphone 4 feels like a low end android phone… I was perfectly happy with iOS 6…

Can I safely update to ios7 without the original SIM card?

Guys i have an iphone 4s running ios 6.1.3 and I'm wondering if I can update it to ios7 without the original sim from Verizon, right now I'm just using it like iPod,.by the way I'm from the Philippines and the phone was just given to me.

Move Itunes library to Other User on same PC (Windows)?

My boyfriend has recently purchased an iphone and we don't want to share an itunes library. I had created a library on his laptop for myself but now he will need his own. I have created myself as a new user on the PC but I don't know how to transfer the music over so that only I can access this library? Then he could import all his own music and have his own library.

if this is not possible is it possible to create 2 libraries within itunes so that I sync my phone to the existing library and he can sync his to the new one?