Wifi-connection problems

Hi everyone,
So, I have a Macbook from 2011. About two months ago, my long-time router died. I bought a new one, and I had trouble loading certain web pages, plus it was very slow. My friend had no trouble with his PC, though Google was acting weird for both of us. I then got another router, and my Mac is still very slow on it, though all pages load. My speeds are: 1.5mbps download, 4.5 upload. Friends who come over get 25mbps download. Also, my Mac gets about 20mbps download with other networks.
So...what does this mean? I just installed Mavericks and increased RAM (and now the Mac is faster, but still has trouble with lots of downloads and Netflix), I had a Mac expert look at the thing, and we still can't figure out why 1) my Mac cannot do well with my network when others can, and 2) my Mac connects fine to other networks.
Any advice welcome! Thanks a lot. Oh, and I've tried Firefox, and it's a little faster (was also having trouble playing Netflix on Safari--suddenly won't play well or load well on that, but does pretty ok on Firefox). Still the slow download and upload speeds.
Thanks so much for any advice!

Reset the router and set up a new account, and in wireless opt for the 5GHz band if it is a dual band router.

Thanks. Do you mean set up a new Mac account? I've already reset the router many times, but it's still slow.

Did you set it up for the 5GHz band and a new Account in System Preferences > Network?

I don't have a dual-band router...

Sorry thought any new router would be dual band however proceed with a new account under Network and fingers crossed. Obviously from your description it is a computer network problem rather than your service.

Thanks for the help! But, sorry, I'm a bit illeterate in these matters: Do you mean, create a new network after reinstalling the router? Can I create a new network with present router? How do I do this? Thanks for your help!! Sorry if I sound rather dumb...;P

Help..!

I just tested the Mac with another network, and the speeds were much greater...So, it's definitely in how it connects to my home network. So strange!

Any other ideas? Very grateful...