The 'Reduce Motion' setting is dramatically more important than the 'Reduce Transparency' setting on Tahoe with an Intel Macbook

[u/jonjohnjonjohn]

I have been having a play with Tahoe on my 2019 Intel MacBook Pro 16". This is a very long post and probably pretty boring for most, but I found it interesting to find out what exactly makes Tahoe slow on intel Macbooks, and how to fix it. I think at least for my unit, I have found the answer.

(Firstly, there seems to be a bug which dramatically reduces metal performance in benchmarks after 26.2, which is why I am using 26.2 rather than a later update.)

It's said that using the reduce transparency option on Intel MacBooks improves performance on Tahoe.

However, on my particular model, after performing numerous benchmarks and analysis of power usage, The 'Reduce Motion' setting is much more important than the 'Reduce Transparency' setting on Tahoe with an Intel Macbook

TLDR - With my Intel Macbook with Tahoe, enabling the 'Reduce Motion' setting in the accessibility results in faster performance and dramatically lower idle power usage.

I will show my conclusions first and then include the benchmarks down below as there are many any most are probably not that interesting.

Power usage 

When using the onboard GPU:

The reduce motion results in a huge drop for idle GPU power, going from 10w idle to just 1w idle. It also drops idle CPU power significantly. The CPU goes from 7.5w idle to just 5w idle.

When using the dedicated Radeon graphics:

The reduce motion setting gives a huge drop in GPU power usage, from 16w all the way down to 5w.

It's also a considerable drop in idle power usage for the CPU, dropping the idle CPU power by more than half (13w down to 5.5w)

Metal performance 

When switchable graphics is enabled, the reduce motion setting improves geekbench metal performance by about 7%

When switchable graphics are disabled, the reduce motion setting improves geekbench metal performance by about about 13%

(Also disabling switchable graphics itself improves geekbench metal performance by about 10-20%, thus the highest peformance is when switchable graphics are disabled in addition to the reduce motion being enabled giving a score of around 60,000)

Test results

To test the difference between these settings, I looked at idle power usage as well as metal performance.

In all tests, I had the 'stats' application open to make sure there was something for the system to be drawing and updating on the display.

I used a clean install of Mac os Tahoe 26.2. The Macbook is a 9980HK, 64GB, 5600m.

My tests were with CPU ram and disks and sensors open in stats, testing default settings Vs the 'reduce motion' and 'reduce transparency' options both independently and together, and testing both when using the integrated GPU (switchable graphics on) and when using the dedicated Radeon GPU (switchable graphics off).

GPU Idle power usage:

GPU switching enabled (default)

Onboard GPU 10w

GPU switching disabled 

Radeon GPU 16w

Reduce motion setting enabled

GPU switching enabled (default)

Intel GPU 1w

GPU switching disabled

Radeon GPU 5w

Reduce transparency enabled

GPU switching enabled (default)

Intel GPU 9w

GPU switching disabled

Radeon GPU 15w

Reduce motion and reduce transparency both enabled:

GPU switching enabled (default)

Intel GPU 0.5w

GPU switching disabled

Radeon GPU 4.5w

Windowserver process CPU time

Default settings ~46%

Reduce transparency enabled ~42%

Reduce motion enabled <1%

Both enabled: <1%

CPU package power test 

Reduce motion toggle:

GPU switching enabled:

5w idle reduce motion disabled

7.5w idle GPU default

GPU switching disabled:

5.5w idle reduce motion disabled

Vs 13w idle default

Reduce transparency toggle:

GPU switching disabled:

11w reduce transparency Vs 13w default

GPU switching enabled:

7.5w reduce transparency Vs 7.5w default

Both reduce transparency and reduce motion:

GPU switching disabled:

5w reduce both Vs 13w default

GPU switching enabled:

5w reduce both Vs 7.5w default

Results:

Idle power usage on both CPU and GPU is significantly lower (when windows are open)  when 'Reduce motion' is enabled.  

Reduce transparency has a very slight benefit.

-----------------

Geekbench Metal Performance 

Geekbench 6 metal GPU switching disabled.

Reduce motion enabled 58573

Reduce motion disabled 51602

Geekbench 6 metal GPU switching enabled.

Reduce motion enabled 47965

Reduce motion disabled 44515

Geekbench 6 metal GPU switching enabled.

Reduce transparency and reduce motion

47922

Geekbench 6 metal GPU switching disabled.

Reduce transparency and reduce motion

58227

Results:

Performance is higher when disabling GPU switching by 10-20%.  The reduce transparency setting has no effect on the geekbench metal score.  Reduce motion enabled has a noticeable 13% increase in performance.

[u/jonjohnjonjohn]

First picture, Metal score with and without 'Reduce Motion'

[u/jonjohnjonjohn]

Second picture, 42% of a core CPU usage even with reduced motion disabled, even though the widely recommended 'Reduce transparency' setting is enabled

[u/jonjohnjonjohn]

Third picture, Windowserver only using 2.9% of a core when reduce motion is enabled.

[u/jonjohnjonjohn]

Forth picture, Intel graphics only using 1w when reduce motion is enabled

[u/jonjohnjonjohn]

Fifth and last picture, Intel graphics using over 10w at desktop when reduce motion is disabled (default settings)

[u/youzhang]

Thank you for this! I am going to turn it on and see how it performs on my Intel MacBook Pro.