i3S data with cesium?

Good evening,
My goal is to test and compare the performance of 3D tiles VS i3S in :
o storing large volumes of data (volumetry).
o displaying (data display time)

I have currently 2 larges 3Dtiles files. For information, i work on windows OS.
a. Is there a way two convert those two 3D tiles toward i3S format ?
b. Is there a way to load i3S format with Cesium (Cesium-ion, cesiumJS,etc.)
c. Could you recommand some ways, some tools in order to make the performance test (data display time,etc.)

In advance, thanks a lot for your help.

There are currently no plans to add support converting and loading I3S in CesiumJS. What kind of performance are you looking for?