Do themes slow down Ubuntu's performance?

Question

Ubuntu (12.04) comes with pre-installed themes. If I were to install extra themes, then does running them slow down performance in any way, even slightly?

In other words, are the default themes technically the quickest (in terms of rendering, animation, etc)?

Answer 1

No, The default themes are not the ones that are technically quickest. You can find many themes which are more quicker than the default themes. (It does not mean, the defaults are slower, they are good for default and branding. I like them also)

does running them slow down performance in any way, even slightly?

It depends, some themes may be faster than the defaults, some may perform slower. A rule of thumb is, the more the gorgeous, the more they use resource (hence slower).

You can find many themes here.

I found this PPA to be very good for themes. It is webupd8 themes PPA. To add and use the PPA, use these commands.

sudo apt-add-repository ppa:webupd8team/themes
sudo apt-get update
sudo apt-get install zukitwo-theme

Also you can install other themes then zukitwo. You must install ubuntu-tweak or myunity software to change themes.

sudo apt-get install myunity
sudo apt-get install ubuntu-tweak

Answer 2

Themes are basically a bunch of images (and there might be an XML that needs parsing) so as long as you keep the images small you will not notice them slowing down your system even when using your own custom made themes.

Answer 3

For the Unity 3D desktop you can disable blur with CCSM or probably MyUnity, that may slightly improve speed.

For window theming there exist a number of rendering gtk-engines with different capabilities. Some are fast and still look nice and modern like the default in Ubuntu called Murrine, others look ugly and offer no significant performance benefit like Redmond. There exist no fallback rendering engine like in Windows where you can disable the theming service.

The rule of thumb mentioned above 'more gorgeous, more resources wasted' is one widespread superstition that does not generally apply. Drawing a few shapes and gradients more or less will not impact the overall performance of your system. Choosing an uglier theme will not give you a performance boost you can utilize. Unity and other modern desktops utilize the raw performance of your box that you paid for and would otherwise not be used at all.

It does not make sense to save resources and never use them, it's about how to use the available resources to make the most out of it.

If you haven't already, buy a SSD.