Just based on the code you showed, the main suggestion I have is not to recreate the scatteredInterpolant object every time. Just change the Values property to each of your different data sets. That way the effort to create the internal information necessary to perform the interpolation based on the coordinates (which are the same each time) doesn't need to be repeated. See the "Replacement of Sample Values" example on that documentation page.
Alternately if you're using release R2023b or later, you could use the functionality introduced in that release to "Interpolate multiple data sets simultaneously" (see the Version History section of the documentation page.)
