Lag come with the new update's.
I was expecting to be no lag anymore now that I'm using and Mac mini with Apple M1 and it have been great, until now.
In Single Player mode regardless of an older world map or a fresh new world map, lag have been an issue since the update of 1.20.5 and 1.20.6 and even 1.21. My computer is a Mac mini with Apple M1 16GB RAM/ 512GB HD macOS Sonoma 14.5.
The steps to reproduce this issue is simple;
After the luncher.
Press play after you chosen a version, eg 1.20.5 or 1.20.6 or 1.21.
Then chose Singleplayer.
Chose an old world or make a new one with the default settings.
Play away and be stopped and started with the all new Lag.
Please see the requested vedio link below....
Attachments
Comments

We do not have enough information to find the cause of this issue.
Please record a video of this happening and attach it to this report.
If you are on Windows, you can use Windows
+Alt
+R
to open a built-in app for recording game footage.
If you are on Mac (Mojave or later), you can use Shift
+Command
+5
to open a built-in app for recording your screen.
In case you don't have a program to record videos, we recommend using the free recording software OBS.
In case the resulting video file is too large to be uploaded to the bug tracker directly, please upload it elsewhere (e.g. as unlisted video on YouTube) and link to it here.
This issue is being temporarily resolved as Awaiting Response. Once the requested information has been delivered, the report will be reopened automatically.
Quick Links:
📓 Bug Tracker Guidelines – 💬 Community Support – 📧 Mojang Support (Technical Issues) – 📧 Microsoft Support (Account Issues)
📓 Project Summary – ✍️ Feedback and Suggestions – 📖 Game Wiki

Please see the requested vedio link below....

The lag seems to happen when you cross a chunk border.
Would MC-229115 describe your issue? If not, please look over the mod notice on MC-166005 and see if any of the mentioned reports there match the behavior you're observing. Lag spikes when crossing chunk borders can happen for any number of reasons, so it's important to know the exact cause for why or how.

I was wrong, it seems to be a combination of GC, Profiler, Lighting recalculations. Amplified by using non-vanilla launcher. Viradex your comment distracts from the actual causes.

This report is currently missing crucial information. Please take a look at the other comments to find out what we are looking for.
If you added the required information and a moderator sees your comment, they will reopen and update the report. However, if you think your update to this report has been overlooked or you want to make sure that this report is reopened, you can contact the Mojira staff on Discord or Reddit.
-- I am a bot. This action was performed automatically! If you think it was incorrect, please notify us on Discord or Reddit

The issues is still here. It have not yet been resovled. Please see my new recording.
As for the Launcher, please see the photo.
[media]


Please be aware that my Mac is the newer Apple arm M1 cpu, not Intel. It true that Mac with an Intel cpu will have lag issues with Java Minecraft. It wasn't an issuse with the Apple M1 up to the 1.20.4 update. After that at 1.21 and 1.21.1 updates the lag is now there regardless of playing offline or online.

Ok still try both fixes, let me know if either works or if neither does.

All good with the enabling of ARM64 java runtime in the launcher settings. This actually fixes this problem, thanks to AdyTech99 suggestion.
Why it was switched off when the update happen is anyone guess.
how is this a bug?