I am running xubuntu for almost 5 years now, and i switched from few versions and previous versions of xubuntu were pretty fast but latest one 16.04 is kinda different, i recently switched from 14.04 to 16.04 on my laptop and with previous version my laptop was working pretty fine and fast.

Now i know it's not the newest high end laptop but this is pretty decent laptop and good configuration even for today requirements. I can play even latest games on it and windows is running very fast.

The laptop is Toshiba Qosmio F50-125 with specs

Intel Core 2 Duo P8600 processor clock speed : 2.40 GHz Front Side Bus : 1066 MHz 2nd level cache : 3 MB

4GB DDR2 RAM 800Mhz

Nvidia 9700 GTS 512 MB DDR3 dedicated ram

I have 120GB SSD as my main drive, and 400GB HDD from laptop i put it in DVD drive instead of DVD.

The problem is that i noticed that my CPU never gets used more than 70-80% and at that point my laptop starts running slow, the browsers like firefox, or chrome starts with lag and freezes from time to time, if i watch the movie i can't do anything else because it starts skipping frames, and i can't even try to load FHD video from youtube.

I have latest proprietary drivers from Nvidia. And i know that my laptop is capable pushing this all with no problem i could watch even 4k video on youtube on 14.04 xubuntu.

As per Fabby suggested i took a screenshot of my ram usage enter image description here

And also i taken system monitor to see the usage of pc. At the time i made a screenshoot you can see that i have a few services that can stress pc and use resources like xampp with mysql and apache running, radio tray which plays radio music, and few others. And also firefox of course and firefox was playing 720p video.

enter image description here

You can see that i have enough memory and also that my CPU is about 70% but i feel alot of lag on my video like it's on 20fps

I have just checked this and what the hell is this driver? From the name i can guess it's for my Intel CPU, but Unknown: Unknown? that is that. enter image description here

I also checked my GPU use when watching video and it's not nearly to struggle, almost don't feel the video.

enter image description here

  • I've got the same kind of config on plain vanilla Ubuntu and that is still running fast, so Xubuntu should be faster. Count you post memory info (free --human) when this is happening? – Fabby Oct 21 '16 at 22:29
  • I don't think the memory is issue, i have running firefox with alot of tabs, atom.io editor, krusader, radio tray, thunderbird, and xampp in the background, and in panel have weather, network monitor, system load indicator. That are processes that i paid attention that are running right now and when i played the video on 720p it got alot of lag. The free --human returned total used free shared buff/cache available Mem: 3.8G 2.3G 589M 54M 963M 1.2G Swap: 4.7G 76K 4.7G I think its more of xfce – Aleksandar Đorđević Oct 21 '16 at 23:14
  • Hard to read here. Please edit your answer and provide the output there. ;-) – Fabby Oct 21 '16 at 23:17

With only 4GB of RAM when you have browser tabs open and watch movies you can run out of RAM. When things slow down open the terminal and type:

free -t

and something like this will appear:

              total        used        free      shared  buff/cache   available
Mem:        8032676     2723200     1758504     1706696     3550972     3233708
Swap:       8191996           0     8191996

This shows how much free memory (RAM + SWAP) you have available. As RAM approaches 95% usage and/or SWAP approaches 65% usage you will notice slow down and possible lock up's if Kernel version is less than 4.6.

In Kernel version 4.6 OOM (Out Of Memory) Killer was revamped to not crash systems as easily as before. Ubuntu 16.04 uses Kernel version 4.4 by default and Ubuntu 16.10 uses Kernel version 4.8 by default but you can upgrade at will albeit at the risk of not having an officially supported kernel version.

When using your browser you will find some websites will eat up RAM like kids in a candy store. In Google Chrome press Shift+Esc to bring up system monitor which will show you how much RAM each open tab is consuming.

Sample screen:

Chrome RAM

  • I know that my firefox is consuming alot of ram but usually i get around 3gb taken in rare cases (when i open large file in photoshop) it gets eaten whole ram, and believe me it's not the ram issue with lag. I feel when swap starts, it freezes the pc for a few seconds for a few times every time i get to max ram. This more looks like it's a lag when you don't have proper graphic driver. – Aleksandar Đorđević Oct 22 '16 at 2:22
  • Your system will slow down before you swap fills up. In my tests new applications refuse to start when RAM hits 95% and SWAP hits 65%. It is more important than CPU% sometimes (if not most). – WinEunuuchs2Unix Oct 22 '16 at 2:37

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