They have been improving performance with things like OCS and Network Bind/Occlusion Culling. However, we probably won't see any big "leaps and bounds" kind of performance improvements until the Server Meshing is up and running. Right now, the servers and network are the bottlenecks, and no matter how powerful your computer is, it can't compensate for the back-end server/networking issues.
Unfortunately, and fortunately, they've also been adding more and more content to the game, such as Hurston and its 4 moons, and the upcoming ArcCorp with its 2 moons, and there are quite a few more players per instance/shard/whatever than there were 2 years ago. That adds more and more for the servers to process, and without the meshing in place, the servers are having a difficult time trying to keep up. While the meshing needs to be their highest priority, and I'd be surprised if it was not, there are probably only a dozen people or so that are dedicated to that feature; its a specialized skillset, and you can't have too many people working on something at that level without tripping over each other. Meanwhile, the rest of the companies still need to keep making content.