Single Part Weldment Vs Assembly as weldment, which is more performant?

Ive been doing some research on this but cannot find anything on actual performance of single-part file vs assembly of individual parts. Is there any significant performance change between using single part weldments with Solidworks built in functionality, vs building assemblies from individual parts? It seems to me that single parts should be more performant but Im not sure and want to supplement my own testing.