Sluggish PC on Ubuntu - Page 2

Okay, so my problem with jerky video (YouTube, etc.) probably comes from the hardware, right? I’m planning to upgrade it little by little anyway (memory stick, hard drive, and graphics card to start). Thanks for your help, I’m waiting for a response and I’ll mark the post as resolved.

You install a 3D game, and it runs perfectly smoothly, so your hardware isn’t the issue!
This must come from your internet connection.

My internet connection goes through an Ethernet cable (the one provided with the box). What can I do to get a better connection? I ran a test and here are the results: download speed = 484 KB/s and upload speed = 75 KB/s.

I have:
download speed = 212 KB/s and upload speed = 31 KB/s
and YouTube videos are smooth. So it doesn’t come from there!
If only your videos are jerky, it probably comes from Adobe Flash Player 10 (right-click on one of your videos to see if you have version 10).
There are many problems with this software on Ubuntu .

yes, it's indeed version 10 that I have.

Here is a post that might help if you have a problem only with Adobe Flash Player 10:

http://forum.ubuntu-fr.org/viewtopic.php?id=316789

For example, I have to disable Compiz Fusion (the 3D) if I want to watch the video in fullscreen.

I uninstalled and reinstalled Flash Player 10. It’s better than before in a small window, but not so good in full screen; it lags a lot and it keeps shrinking on its own.

Many people on Ubuntu have a problem with Adobe Flash Player 10.
See this forum dedicated to multimedia issues on the official site:
http://forum.ubuntu-fr.org/viewforum.php?id=17
Now it's up to you to see if that's all that slows down your PC.

okay thanks for everything, I’m marking the topic as resolved.