Board Thread:Bug Reports/@comment-25869554-20160307193726/@comment-26172435-20160312124815

When you open your launcher, it shows the option to select a launcher profile at the bottom left of the launcher window. Edit the profile you use to play Forge 1.7.10 with the LOTR mod. The 'Edit profile' window has a section on advanced java settings in the bottom of the window. That holds the JVM flags. Edit the appropriate field to set the right flags, as indicated above by MilkMC.