FAQ
A1. Reduce "view-distance" in your server.properties file. Usually, you can go down to 6 without visible changes, or 3 if you have a very large server.
A2. Try updating Orebfuscator to latest version and Craftbukkit to latest RB.
A3. Read more about reducing CPU load at How to properly configure Orebfuscator
A1. You should be warned at login if you are bypassing Orebfuscator. This is caused by the bypass checks done on OPs and players with permission "Orebfuscator.deobfuscate". You can use commands "/ofc disable op" and "/ofc disable perms" to disable these bypasses so that you can see the obfuscated world.
A2. If you use Engine Mode 1, some ores will be shown. This is done by design. You will have about 10% of ores shown to hackers because these ores are exposed to caves, so players should be able to see them.
WARNING: Orebfuscator does NOT hide caves. It's technically impractical to do so (would take too much CPU).
TRY THIS:
You can try adding either "-XX:+UseParallelGC" OR "-XX:+UseConcMarkSweepGC" (not both) to the command line of the server startup script if you are experiencing OutOfMemoryException.
This changes how Java free memory and allows memory to be freed more often in some cases.
Other answers: If your server is really low on memory. ADD MORE MEMORY TO JAVA by adding the switch -Xmx#M or -Xmx#G (Replace # with desired number)
ex: "java -Xmx4g -jar craftbukkit.jar" will set heap size to 4GB
Read more about memory issues and how to solve them at How to properly configure Orebfuscator
A. Update to the latest version of NoLagg and Orebfuscator should fix the issue. If it doesn't, please give a shout to both me (lishid on bukkitdev) and NoLagg's creator BergerKiller (also on bukkitdev).
A1. In most of the cases, they are x-ray hackers who tries to get the server admin to remove the anti-xray mod so they can start hacking. Make sure you (the admin) confirm the problem yourself and/or by other trusted members of your server.
A2. You should first attempt to clear cache (with command "/ofc clearcache") and ask everybody to logout/login. If that does not fix your issue, ask about it on the forum.