Youtube videos

[Lirange]

What determines how fast youtube videos can load? Internet connection or computer? I used to be able to watch youtube videos without having to wait for it to load but nowadays i'm lucky if i'm able to do that on the lower quality. =/ I would love to watch in 720p but it takes forever to load. Btw, does all computer monitors have 1080p? I definetly notice a difference between 720p and 480p but last time I checked, I didn't see much of a difference between 1080p and 720p.