Lag, rubber-banding and low FPS — telling the three apart

Three different problems that all get called "lag" and have completely
different fixes. Working out which one you have is most of the job.

Low FPS — your computer

Symptom: everything is choppy, including menus and your own inventory. The
world is smooth for other people.

Yours to fix: lower render distance, turn off fancy graphics, close
whatever else is running, use a performance mod. Render distance is by far the
biggest single lever.

Rubber-banding — your connection

Symptom: you walk forward and get snapped back. Blocks you broke reappear.
Your own frame rate is fine.

Usually yours: wifi rather than cable, something else using the
connection, or a VPN adding a detour. Test on a phone hotspot — if it is
better there, it is your network.

Server lag — ours

Symptom: everybody is affected at once. Mobs stand still, chests take a
second to open, chat arrives late. Your FPS is fine and you are not being
snapped back.

Ours to fix, and worth reporting. What helps us:

• Roughly when, with a timezone.
• Where you were, and what was around — a big farm, a lot of items on the

floor, a lot of players in one place.

• Whether it was everybody or just you — ask in chat.

The one you can cause

Redstone builds, mob farms and item piles that measurably hurt performance get
removed without replacement. That is in the rules, and it is not a judgement
on your build — it is arithmetic about everyone else's tick rate.

If you are planning something big, ask on Discord first. "That will be fine"
costs a minute. Getting it removed costs a weekend.

Quick self-check

You see	Others see	Likely
Choppy menus too	Fine	Your FPS
Snapped back, smooth FPS	Fine	Your connection
Delayed everything	Same	Server — report it
Fine, then terrible near one spot	Same near that spot	Something built there