Why software written in C++ Qt are more energy efficient?

[murtio]

I have been using software written in Qt [0] across different OS. Many of them were written specifically to be used in GNU/Linux, such as Okular [1] and QBittorren [2]. Others, such as VLC [3], were later shipped to other OS. In the case of VLC, only the GUI was written in Qt.

I have noticed that Okular and Qbittorrent were very energy efficient in GNU/Linux. But I didn't expect it to be the case in other OS such as MacOS.

Recently, I used Homebrew to install Okular on MacOS, and I compared it to other PDF readers such as Adobe Acrobat Reader and Skim. Okular was superior in terms of energy consumption.

RESULTS: Energy impact for 12h:

Adobe Acrobat Reader = 0.9

Okular = 0.4

QUESTIONs: Is this always true? Do Qt software always perform good in terms of energy consumption, across OS? Why is that?

[0] https://en.wikipedia.org/wiki/Qt_(software)

[1] https://en.wikipedia.org/wiki/Okular

[2] https://en.wikipedia.org/wiki/QBittorrent

[3] https://en.wikipedia.org/wiki/VLC_media_player

[sigmaprimus]

I seem to recall from my work with low power microprocessors, it had to do with how your compiler instructs the cpu to preform bit wise operations. I believe it has something to do with the internal pullups drawing power due to the state of the data in the register at rest.

Eg it is more efficient(or less) to instruct a loop to count down from 50 to 0 rather than up from 0 to 50, both methods result in 50 cycles but one is more efficient.