I am using Lenovo computer having the following configuration: 516 MB RAM and 3.06 GHz CPU
When I installed 11.04, the system was getting very slow. From the Internet, I read an article that Lubuntu desktop are very light-weight desktop, so I installed it in Ubuntu. When I switched to Lubuntu desktop, the system got a little bit faster, but when I open YouTube site or some other video-streaming websites, the system gets slower.
1. With the 516 MB RAM it would be very advisable to use LXDE/Lubuntu. I use it with 1GB RAM and the difference is huge compared to using Unity or KDE, and very significant compared to using Xfce/Xubuntu.
2.The way your computer lags in playing flash in Youtube is a different issue, as it is related not to your RAM or CPU, but to the graphic card (GPU). You have a powerful enough CPU but the Adobe Flash plugin has the odd quality of avoiding using CPU and putting all the load on your GPU. See this question and the answer there and the comment of izx:
Flash 11+ "attempts" (poorly, it looks like) to use the GPU (hardware) to "decode" the video instead of the CPU (software). Decoding is a fairly computationally intensive task, but most modern CPUs (except Atoms) will deal with 1080P HD without breaking a sweat. It appears that Flash doesn't seem to obey that checkbox and still tries to use the GPU.
(meaning the checkbox in Adobe Flash Player Settings telling it not to use hardware acceleration)
Odd enough, using the HTML5 version of Youtube (which some recommend as a solution in this case) still brings my GPU to 100 degrees Celsius.
It seems that there are ways to put your CPU (more powerful) to work, and not your GPU (which is less powerful). My favorite solution to this is opening youtube in external player.
Lately I could not use the OpenWith Firefox addon to open youtube videos in VLC, so I recommend especially the Firefox add-on Smplayer context menu or the Youtube player that comes with SMPlayer (smtube). Install in Terminal (instead of Synaptic, which seems to give a version of SMPlayer that does not allow editing its Toolbar)
sudo add-apt-repository ppa:rvm/smplayer
sudo apt-get update
sudo apt-get install smplayer smtube
or just Alt-F2
or
To create a desktop icon the Lubuntu way:
3.To kill processes like you do in Windows, you need to start a Task Manager.
There a different of this kind (gnome-system-monitor, lxtask, xfce4-taskmanager) and according to the desktop environment there are different ways of setting keyboard shortcuts for applications. But that would mean creating a new question (you already put two of them here!)
To kill now active window:Alt-F4.
Killing a process is easy once you know how. Assuming it's a GUI program (a program with a visible window), you can kill it this way:
xkill and press Enter.If this doesn't work for some reason, instead of xkill type ps -A (capital A is important). This will bring up a list of running processes, with process IDs at the left. To kill a process, simply type kill [ID]. For example, if the entry for Firefox looks like this:
15686 ? 00:24:23 firefox
you will have to type kill 15686 to kill Firefox.
Install the software called MiniTube. It is free for Linux and will greatly help your play YouTube videos, since it doesn't use Flash. Additionally, it allows you to skip all of the advertisements.
Lubuntu is great and not as bloated as Ubuntu or even Linux Mint.
Good Luck!
