GameCube and the Wii emulator Dolphin had a progress report posted up in late December, and it's looking really good, especially so with their performance optimization work.
As usual plenty of new features are coming in like support for WiiConnect24, a service for staying connected online but it was terminated by Nintendo (but alternatives like WiiLink and RiiConnect24 exist). Now Dolphin should work nicely with it.
More exciting though is that their team has been doing a lot of work with Vulkan lately including the use of the Vulkan Memory Allocator, which gives them better memory management. Their optimization continued, thanks to the release of the Steam Deck where they realised they could do better. One game in particular stuck out with Super Mario Galaxy (Wii) not performing like it should, and they ended up finding something they were doing eating up a lot of CPU time which as it turns out was a regression from two years ago. After sorting that, it was optimized even further and in their simulated Steam Deck testing they showed performance going from 85FPS to 140FPS.
Image Credit - Dolphin Forum
They also made it clear some direct Steam Deck testing showed a clear improvement too with "Super Mario Galaxy (and a little of Super Mario Galaxy 2)" performing now "at full speed and 2x Internal Resolution without any noticeable slowdown".
Overall, sounds like a nice performance win for all users but especially those on Steam Deck. On desktop though they said they saw Super Mario Galaxy games get an improvement of about "30%" even when running at "4x Internal Resolution" but not everything has a big jump, some games only saw a very small increase.
Lots more in their progress report like a reduction in stuttering with more optimization work going into the Ubershaders system, improvements to their FPS counter, an Android GUI refresh and so on.