As you are looking to get a lot of feedback quickly, perhaps this question is probably better asked in our Studio One 3 Community forum or on the Studio One FaceBook Group.
We would probably say the number of plug-ins that you can run simultaneously depends on the the performance of each plug-in. There are no limits on how much each plug-in can take in terms of CPU or RAM, so one convolution reverb with heavy processing can take a lot of CPU just by itself. The answer is subjective. For the best performance we would suggest a Mac Book Pro. However if you need / prefer Windows system, then consider contacting a company that specializes in systems built for audio production and not gaming such as PC Audio Labs or Sweetwater (if you're in the USA), Molten (for Europe) or AAVIM in Australia.
If you're looking for more horsepower, then consider going with a desktop, as laptops are built for energy conservation so the CPU will always be looking to conserve power to keep heat down. Whereas with a desktop you can run additional cooling for additional power for CPU and RAM needs.