Talking about Archery lag, I'll snip some parts of an article I read and translate them,
mix in a bit of my thoughts and tell you why Nexon cannot fix lag.
Here's an MMORPG's standard packet/data relay framework:
1. Input is received by client (e.g. Click X, Y coordinate on a map)
2. Send the input data to server
3. Check data validity (see if it's modified data or not)
4. Apply data to server
5. Send response from server to your client
6. Your client draws the result (e.g. Move to X, Y coordinate)
BUT. Nexon and DevCAT could save a lot more money by reducing the data sent to and from server.
How? Modify the engine (the almighty Pleone) and cut down data communication between client and server.
Here's what Pleone engine actually works:
1. Input is received by client
2. Your client draws the result first, screw the server, we don't need your opinion
3. Repeat 1 and 2 few times
4. Send the data to the server
5. Check data validity, apply to server, send response from server to your client
6. Then client checks if the data from server matches your data in step 2
There are 2 problems with Pleone's framework:
1. Server data overrides client data. - While it is an efficient way of preventing hacks, it also means if there are screw-ups if any packet is lost along the communication between your client and server.
2. The repetition of step 1 and 2. - Less communication = less server usage = less cost. But it also means data from server is less reliable, as your client is updated less frequently.
This can never be fixed.
Never will be fixed unless they adapt Physics engine and build the game from gound up.
Also, there is a part on CPU and lag.
In short, that part says "In the early days of Mabinogi, CPUs were more dominant part of gaming rather than GPUs in general gaming environment."
I don't think more explanations are needed.
tldr; Lag cannot be fixed.
Source: http://www.mabinogi.pe.kr/bbs/zboard.php?id=forum&page=1&sn1=&divpage=1&sn=off&ss=on&sc=on&select_arrange=headnum&desc=asc&no=944