From my understanding (and in practical experience). The slave computers will act in parallel. So whether you have 1 slave, or 20, the amount of latency that VEPro needs will remain the same, given all other variables remain the same. I currently have 2 salve machines, and I started with 1 slave machine, and my latency has always remained the same (buffer size of 2, adding 2x my DAW buffer size). Or at least my buffer size that worked. What will be a larger factor is how low can you push the buffer size before VEPro can’t handle the real time requirements, and how well the sampler can handle the real time load as well. Kontakt seems to do well, EW Play (old version) has had issues for me. And finally if you are running your samples off of a SSD or HDD will make a substantial difference in how low you can push the buffer size. Use an SSD, but you don’t need a super fancy and fast SSD, most any SSD will do, just so long as it’s from a reputable manufacturer it will perform just fine. You are mostly loading samples into RAM, and that just needs to be done in an efficient manner, which HDDs aren’t great at doing.