Multithreading is an important issue right now. Taking advantage of it in
jME3 is critical. Some areas where multithreading can be used:

• Skeleton animation, mesh skinning
• Particle update
• Physics
• Networking
• Input polling
• OGG/Audio streaming
• Resource loading
• Terrain streaming

The details on how to implement these areas using multithreading will be
specified later.

Some parts of jME3 are already multi-threaded:

Physics runs in a parallel thread.
Networking runs in a parallel thread.
Audio and OGG streaming is done on a parallel thread.
Terrain streaming/LOD is done in a parallel thread.

jME3 is still missing asset loading on a separate thread, which can be critical if the application loads assets dynamically.

The AssetManager is the last part of jME3 that needs to take advantage of multithreading.

Reference on googlecode: https://code.google.com/p/jmonkeyengine/issues/detail?id=94