Windows 7: Youtube Video not streaming cleanly

i have noticed that youtube and vimeo video's aren't streaming correctly on my PC, i have very quick internet and the videos load quickly, but every 5 - 10secs the vid justholds for a second then continues streaming, i am using latest firefox as a browser, and my PC is high spec so not sure why this could be.

What antivirus are you using?

^^^ avira antivir personal

I see no reports of Avira's Web Guard causing slow downs. Do you have any other real time protection/web filters?

i use "NoScript" with firefox, thats all though

Take a look at this post: My Windows Live Mail has Stopped Working/Workaround.... apparently Avira can slow things down. Use Microsoft Security Essentials instead.

I have the same issue. Only Firefox does it. I've searched around, and it seems it only started after Adobe released it latest Flash update. I've tried everything. Uninstalling Flash, Firefox, turning HA off, and nothing works. It's actually on Mozilla's bug site too.

PS My Anti-virus is MSSE, so that's not it.

That reminds me that Steve Gibson, a Firefox fan and security guru, claims that they broke it ever since version 4 so he uses the last version immediately preceding 4.0: "...I went back to 3.6.23, which is the last one prior to 4, which they are still maintaining, and no problem at all..." Security Now! Transcript of Episode #323

^^^ so i have to use an ancient version of FF to watch video's - that kinda sucks, would you recommend using chrome instead ? haven't ever used it + i'm very comfy using FF, but if chrome is better i'll make the switch... anyone's opinion welcome on chrome v FF... thanks in advance

There are lots of things that can affect Youtube, the browser may not be the problem. It could be the particular video and the time of day you are accessing it; it could be the Flash player; it could be your antivirus or some other process slowing down your PC. I don't watch Youtube enough to say whether it's any worse than usual.