OS keeps getting slower the more time I leave it open

Question

I recently decided against shutting down my Ubuntu machine in office because it took a lot of time to start it and then open all the applications that I would normally require.

After leaving the PC open for a couple of days and coming to use it, the computer was considerably slow. It remained slow for several minutes while I was doing some routine processes and then it caught up. Here is the output of top

top - 10:40:46 up 3 days, 18 min,  1 user,  load average: 0.66, 1.47, 1.42
Tasks: 396 total,   1 running, 330 sleeping,   0 stopped,   1 zombie
%Cpu(s):  3.9 us,  0.6 sy,  0.0 ni, 95.5 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
KiB Mem : 16331284 total,   476144 free, 13993084 used,  1862056 buff/cache
KiB Swap:  2097148 total,   628732 free,  1468416 used.   971580 avail Mem

I want to know why this happens and additionaly how to stop it from happening, also interested in how it improves its performance after some time. I would also like to know how to analyze these things on my own

Answer 1

A linux desktop system periodically "freezing" it usually caused when the system is swapping to disk. This happens when you are running out of free memory and it needs to free things up by moving some data to your much slower swap partition on your hard disk.

Based on your top output, over 85% of your 16GB of memory is currently in use. You can see which applications are being greedy in top by pressing Shift + m, which sorts the list by memory consumption instead of the default, CPU usage.

Certain applications like Google Chrome are known to hog lots of memory and using things such as a tab suspender extension can be useful especially if you find yourself leaving lots of tabs open all the time