Does anyone know why, in my LAN world, everything works perfectly for me, but for my brother who joins the LAN world, every 30-60mins he times out (but doesn't crash)? He has all his settings set to the least-laggy option and doesn't lag often. :/
He's using latest, 64-bit version of Java and running on 3.75GB of RAM set to the FTB Launcher.
Also, after every time he times out it takes 5-10mins for him to log back onto the LAN world which is why this is an annoying problem
This all isn't pack specific. I have had LAN issues with pretty much any pack. I did notice loading into a multiplayer instance could take awhile in this one. I noticed disabling the Journeymap mod took the time until I got a playable framerate down a lot.
Is your LAN world a server or a single player game open to LAN? I have had lots of issues with LAN games that playing on a server fixed. The game is supposed to be setup so that it is always in server client mode now. I found that in practice single player still runs things a little differently. Like saving the main player in level.dat. Even though it shouldn't do that any more. I have had a lot of crashes just trying to look stuff up in NEI on LAN. While I never had the issue in single player or on a server. My computer isn't all that good, yet I still haven't found the pack I can't run a server on it as well as the client. Vaygrim's Chance might be the exception. I get almost no framerate in that. Though adding fastcraft did help a little.
Are both you computers using the same OS? I did notice that Minecraft ran a lot smoother on Linux. On Windows I get frequent complete freeze ups that last a few seconds before the game recovers, and GPU driver crashes. I didn't notice either issue on Linux. Of course I didn't play minecraft for very long on it. Java might be a issue to. Curse still uses java 1.8.0_25 by default. Even though the current version is 1.8.0_91. I am not for sure which one if any are optimal for minecraft though.
Biggest thing is, if you are up for it, Try backing up and transferring your save to a server install on your computer and running that. It is pretty easy to do and might help.
I did notice that computer ability can be key too. I tried playing in someones game when one of the computers could barely even run minecraft. Disconnects and desyncs happened a lot then. I never really got that remedied.
Just noticed the FTB launcher part. It could be connection then. Thinking it might just be that it is LAN.