Serious lagging when streaming movies

Hi, I am new to this forum so I hope I can get some help here.
When streaming a movie it starts off ok then gradually begins to slow down and becomes out of sync. I have an imac on 0S x version 10.5.8. Hopefully someone out there has a fix for me.

Many thanks

There are too many unknowns here - tell us what kind of internet connection, what model Mac, what web site, what size (pixels) 1080p, 720p, 640, etc.

Hi gsahli thanks for your reply, I have a 10Mb broadband connection, an imac and it seems to happen on any site I stream from

Tell us the result of a download test:
Speakeasy - Speed Test

How much hard drive free space do you have? How much RAM?
Is it a G5 or Intel processor?

Which browser? Are they Flash videos or Silverlight?

Are you connected to the net via Ethernet or wi-fi?

The speed test was 8.29 download and 1.00 upload. I have over 400 gig free space. I have a 2ghz intel core 2 duo processor and memory 2gb 667 Mhz ddr2 sdram and I was watching a flash video. I hope that is all the info provided.

Also I amconnected to wi-fi

Which version Flash? (Safari about plugins, Firefox add-ons) I have 11.1.xxx
And what size videos? 720p?
WiFi g or n?

Time to start watching Activity Monitor utility while watching video - what % CPU are the top five processes?

The wi-fi is most likely the issue in my opinion. Try connecting direct to the router with an ethernat cable.

I have flash player version 10,3,183,11 installed.
Thanks to all of you who have responded and are trying to help me.

Appreciate that you've been providing more info along the way!
Go ahead and get the latest Flash Player from Adobe, and then use the Activity Monitor for more clues about what's slowing you down.
I know it's not what you want, but for troubleshooting, find the resolution change icon on the right lower area of Flash and reduce the resolution and tell us if that smooths it out.

I attempted to download the latest version of flash but it gave me the same version that I have been using.

I cannot use ethernet as my son uses wi-fi to connect