I have a Ubuntu 18.04 LTS with 4 GB Ram , NVIDIA GeForce 820M on a Lenovo Z50-70 laptop. My system is running quite slow in terms of GUI responsiveness when I try to use it after keeping it idle for around 7-8 hours. Opening tabs in the browser , using system setting etc become very slow and is also heating up too much (I can feel it). I used free -m and vmstat -S M 10 4 to check memory status. Following is the output for :

free -m 

```
total          total       used        free      shared  buff/cache   available
Mem:           3841        2295         500         122        1044        1192
Swap:          8194        1462        6732

```

vmstat -S M 10 4 output

```
procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 0  0   1462    509     95    949    0    0    15    10   13   28  3  1 96  1  0
 0  0   1462    510     95    949    0    0     5    24  956 2384  4  2 94  0  0
 0  0   1462    514     95    949    0    0     2     6  815 3509  7  2 91  0  0
 0  0   1462    513     95    949    0    0     2    28 1119 3586  9  2 88  1  0

```

From the outputs , it is visible that CPU is idle most of the times, yet psensors show this output 

```
coretemp-isa-0000
Adapter: ISA adapter
Package id 0:  +61.0°C  (high = +100.0°C, crit = +100.0°C)
Core 0:        +59.0°C  (high = +100.0°C, crit = +100.0°C)
Core 1:        +61.0°C  (high = +100.0°C, crit = +100.0°C)

```

I am only using firefox Quantum 67.0 with around 20 tabs. I need to know what is the issue which is slowing down the system. Is it overheating, or excess CPU Usage, or will a full disk cleanup and re-installation help?