But turning off latency reduction might fix it.
It seems like the newest patch for Street Fighter 6 might be causing some performance issues. German Street Fighter player semy28 pointed out on his X account that the game's menus run at a lower framerate than usual, and while gameplay is locked to 60 FPS, various actions outside the game can cause lags and stutters.
It's not clear what causes this, but players have recently discovered one potential cause. Wolfgang and Fatmanatee initially posted similar concerns about the performance ever since the Alex's release.
However, a few days later it seems like Wolfgang and a few others found noticeable improvements after turning off Input Delay Reduction.
While this might not be the true underlying reason for worse performance, if you experience lag after the recent patch, it's worth testing this on your system to see if it results in any improvement.