Why is my browser so slow?

Hi guys, new here I just signed up to ask for some advice. I will tell you everything from the start.

I have had my Dell Inspiron N5110 for about 3 years now could be longer I don't remember the exact date I got it.

For the last few weeks my laptop has been performing quite slow. If i'm honest generally I feel like the laptop is ok but it's just browsers which are playing up. I was obviously on internet explorer at first it became slow so I changed over to firefox which was also slow & then I changed over to chrome which is even worse. I had to change each time because I assumed that the browsers were just rubbish turns out that they can't all be rubbish their must be something wrong on my end.

So on Thursday, assuming I have malware I do a full system scan with my mcAfee Internet security, mcAfee found 2 viruses (I don't remember the names) & quarantined them. So I went over to my browser are the scan & again extremely slow, at certain times the page just doesn't load & ends up giving me a timeout error message.

So, today I installed CCleaner which cleaned my laptop & got rid of all the junk but again my browsing experience is still bad & everything takes ages to load.

I am not sure what is going on here. I have no viruses, the junk has been cleaned, I even took out the time on a friday night manually deleting a load of videos, pictures, files & uninstalling programmes but it still hasn't made the slightest difference.

I would really appreciate any advice you may have. I really don't want to buy a new laptop, I am really attached to this & would just love for it to be fast again.

Please help :(

Salma x