Why does the system slow down under load (especially in games)?

Question

I compare the work of the system on Windows and Ubuntu 20.04.

The problem is mainly under heavy load and the video card and processor.

In Windows, I could open several browser tabs, watch videos on YouTube in parallel and play games.

In Ubuntu, the system itself feels much smoother than in Windows (this is a plus). But during the load, it begins to slow down. The system starts to work in jerks (the same mouse movement). Overheating was not detected in this case.

So the question is this: because of what can the system slow down under load on pure ubuntu?

(TurboBoost - off, powersave - off. The same was in windows and now in ubuntu)

Answer 1

Open System Monitor/Task Manager and notice the RAM usage when this happens the next time. When the RAM is almost full, Ubuntu begins to use a portion of your hard disk (known as SWAP) as a substitute for physical memory, and this makes the system slow, because the data transfer rate to a hard disk is a lot slower than RAM. This may be causing the freezing.

Unfreeze the system

We can disable swap (all memory is transferred to the physical memory), and re-enable it to make the system normal.

When the system almost freezes, open a terminal ctrl+alt+T. Then enter the command to "unfreeze" the system.

sudo swapoff -a && sudo swapon -a

Permanent solutions

1. Decrease swappiness

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   The less the value of swappiness, the system would use the physical RAM more aggressively, and would use swap less.

   Enter the following command

   sudo gedit /etc/sysctl.conf
   

   Search for vm.swappiness and change its value to 10, and save the file.

   vm.swappiness=10
   

2. Disable SWAP permanently

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   Another possible permanent solution would be to disable SWAP. The kernel would automatically close the process that is consuming too much memory.

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