Hello c-r-o-n-o-s,
Which tests you are referring to (are they related to Metashape 1.7 version)?
I suggest to check the timing in the detailed table for the steps that you are interested in (for example, if you are not interested in building mesh from the dense cloud, then the complete processing time, which includes this step is not relevant for your needs).
As for the distributing tasks among several computers, it may be more effective to use network processing solution, as it allows to process the project as a whole, without splitting into several chunks. However, please note that you will need individual Metashape license for each node, if they are supposed to be working in parallel (no matter - as a part of network processing, or in a regular GUI mode).
The possible performance gain depends on the project size, processing batch to be completed and parameters used. For some tasks (like image matching or depth maps generation), the performance boost could be almost 3x (comparing three identical machines to the single computer with the same specifications).