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Why is my Raspberry Pi slow? – Htop

After you’ve had your Raspberry Pi for a while, you’ve made it run a web server, media centre, Remote Desktop and more you might find it’s a bit sluggish. To find out more try out htop.

Traditionally in Linux you would use top, however this generally needs a bit more know-how to interpret the display, and it looks kind of plain.


An ideal replacement for top is ‘htop’ developed by Hisham Muhammad.  This is an ideal process viewer, with simple colour coding and a graphical output to show where resources might be used.  A sample screenshot from my Pi is below:

htop - a process viewer for the raspberry pi
htop – a process viewer for the raspberry pi

Installation of htop

sudo apt-get update

sudo apt-get install htop

Simple, it’s extremely easy to install and has no real overhead when running.

The output from htop

At the top the number 1,2,3,4 are the core status and the more they are in use the further the graph is to the right.

Mem/Swp is the utilisation of your Ram and Swap – Ram is usually filled up in Linux (used for caching)- your swap should not be used too  much, if it is your system will often be slowing down as it swaps memory from the disk (or SD) to Ram as required.

Running htop

Running it is easy – just login to the command line – ssh or local terminal and type


And that’s it!  You can do more advanced things my using the F keys – F9 is a useful one for killing a process that is out of control.

You can resort using traditional top shortcuts – ctrl-M to sort by memory ctrl-P for processor usage etc..

Using F2 you can add more charts to the top section – both left and right sides! Don’t forget to save your new default settings.


If you use another flavour of linux it most likely has htop – try “yum install htop” on centos based systems.

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