The team implemented quite a few updates to performance to the MMO with Update 25's Harrowstorm release, but the team isn't stopping there. With Update 26, Elder Scrolls Online fans can expect to see continued improvements to the MMO, including moving Player Character loading to a multi-threaded process on the server to improve performance.
In addition to the server optimizations, many optimizations are being made client-side, bringing more stability as players play the game. With the upcoming update players should see an improvement to how the client draws in characters in the world around them and more improvements.
You can check out the full post on the Elder Scrolls Online website. Harrowstorm is available on PC now, though console players will be able to tackle the new content on March 10th.