The beta patch including frame optimization is live now for those who want to see whether it’s a huge upgrade (Reddit’s had mixed results).
“This patch introduces an opt-in beta test for the new multithreaded engine features that should significantly improve game performance for most users.
Frame rate increases are most significant when there are a lot of entities in the scene. This means situations with large amounts of combat should have much more stable frame rates. Do not expect significant increases in frame rate in non-combat situations. If you are GPU-bound you shouldn’t expect significant increases in frame rate. To enable this, you need to add “–experimental-frame-optimizations” to the Path of Exile command line.
Please remember that this is a beta test. If you experience crashes or other issues with this feature turned on, we want to hear about it. This feature is expected to be turned on by default in the 2.4.0 expansion release.”