Hello,
I prepared a fix ( Improve support to Matlab R2018b by Edouard2laire · Pull Request #41 · multifunkim/best-brainstorm · GitHub ) and will merge it once github is back online (https://www.githubstatus.com/).
Out of curiosity, i compared 2018b and 2025a versions of Matlab to localize 45 seconds of nirs data. 2018b took 135 seconds. 2025a took 21 seconds.
Edit: The code is merged. You can update the plugin and try again.
Edouard