This may not be a very useful report but when testing a lag machine that used redstone updates to lag the game I noticed adding observer ran worse with alternate-current installed as opposed to with it off. It could be due to interactions with other mods or something but I have not looked into it. I can provide more details if needed.

After doing some testing in the latest (not yet released) update, it does seem that observers are affected, though the effect seems fairly minor, a few per cent at most. Is this consistent with your findings?

I know the source of the performace loss and will look to fix it.

For me it was about 20% increase in TPS for that specific case compared to vanilla but that might be just one specific use case.

That's rather significant. It would help if you could show the specific setup you were using. Which version of the mod are you running currently?

Runnning v0.1.4, also I tested it again and I can't seem reliably reproduce it though so it could have just been coincidence.

This should be fixed in the latest release, so I'll close the issue.