I think that has more to do with CPU usage and or temperature but more CPU usage in your case what you posted for a i7 MBA. I was getting over 1250 and over 3400 on power before any mods. I have gotten over 1300 SC and 3600 MC with power. Ive ran both with power and battery and would say my best scores have been with power.
if this seems to be true with your machine under same conditions then you should call Apple support. You have a problem with your machine.
When running GB you will get your best scores if you are not running any other programs. Your CPU usage should be at or above 98% free.
When on battery and I am not sure at what point but lower battery it seems not to be checking stuff in the background like Photo, Calendar, Accounts, System Update, Windowserver, etc. Seeing I was 98% CPU usage on battery I just ran the GB test while on battery and only 2 hours left of charge 1293SC 4109MC. Then I plugged it in and all of a sudden I am down to less than 65% CPU because I am on power and its checking everything in the background. If I ran the test now it would be total crap like you posted.
Now I wait till its done checking all the background stuff and I am on power with 98% CPU. I run the test and get about the same results. You can see from my 2 screen shots one is on battery and one is on power.
so Generally speaking you are incorrect, and if you are running 10c warmer with power vs battery and can’t determine why, call Apple. I run the same temps either way.
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