Problems with my Samsung Galaxy S3 update?

So I updated my galaxy s3 a little while ago with the latest update… I think it was 4.3 and immediately noticed a couple of problems.
Apart from not liking how messages are when they come in. It seriously delays letting me know I have a message eg. If I'm already messaging someone and they respond I can already have written the reply and sent it before it decides to vibrate and ring the message tone, whereas before it was immediate.

As well as trying to check the time when I need to it averages around 20 seconds before the screen lights up and I'm able to look at the time or even get into my phone again before the update it averaged to immediate to 2 seconds.

The battery life has also shortened significantly, I used to be able to use my phone all day including apps, but now I only get through the day if I use apps to the bare minimum.
As well as that I can no longer use my phone while it is on charge just now my phone is on charge, starting at 12% it has now decreased to 7% just using Chrome to type this question. Before the update I could use pretty much any app or Internet and it would still charge, the charging time has also increased it used to take half an hour to 45 minutes for my phone to charge up and now it takes around an hour and a half.

Also just in general my phone has slowed down a lot, which I feel like is counter to what an update is supposed to do.

Please help me, I don't think my phone is under warranty anymore (if it lasts a year). Thanks.

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