How to know if I need to upgrade my modem/router/internet speed?

When watching Putlocker (a cloud based movie site) I experience poor quality/lag as opposed to some of my friends while watching the exact same movie on the same site. The video kinda looks like someone drew a cartoon movie in the pages of a book and as you quickly flip the pages it forms a little movie… Basically the movies look like a bunch of still pictures strung together. First off I have Chromecast which I'm starting to think is not compatible with Putlocker since when I disconnect the Chromecast and hard-wire my com to the tv this problem is diminished greatly tho still somewhat noticeable. Several people suggested since I have the slowest internet speed which is 2megs. I should upgrade with my cable company to 15megs. Do I need to do this or is 2megs. Plenty? Someone else suggested I get a docsis 3.0 modem instead of the 2.0 I have but again unless I upgrade my internet speed first I believe there's no purpose in doing this since the 3.0 is for faster internet speeds. Also someone suggested that I get a duel band wireless router as opposed to the single band I have now. Their reasoning is that since my household has 3 Iphones, an Ipad, a laptop, and a Chromecast that perhaps my wireless router is overwhelmed. I'm pretty sure its not my laptop since its relatively new. Also would hard-wiring my wireless router help improve this at all? Thoughts? And input on technical requirements for Putlocker/cloud based movies to work optimally? Remember the movies are not technically "downloading" since they are cloud based.

With the amount of electronics in your house i think you should upgrade to 15mgs/s

Usually its the internet provider that is the cost of slow internet so try a different internet provider or try getting new router and seee if it helps. I hope i was able to help you solve your problem

For streaming standard quality videos (around 200MB), you'll need 3 - 5MB/s speed.
For higher quality (take for instance http://funniermoments.com where you can watch cartoon shows for free), you'll need at least 5 - 8 MB/s because then the video files will be around 500MB.
If you prefer to watch movies and tv shows in high quality and without skipping and buffering, I would say 15 - 20MB/s is a minimum.
On Netflix you can crank it down to low quality which only requires a speed of 3 - 5MB/s. That's totally unwatchable on everything other than a mobile phone (in my opinion).
So if streaming tv shows and movies is your thing and you want to have a good high quality experience, you should at least have 20MB/s. But everything above is obviously a plus.
But go to http://speedtest.net/...edtest.net and do a speed test to see what speed you have and call your internet service provider to see if you can upgrade.
Plus / minus 20MB per second would do just fine for your type of use.
If you have an unstable internet line that jumps up and down, you should probably go for something even higher.