From a technical point of view, putting in other projects generates positives and negatives.
Positive:
- Placing on different projects will make your system more modular. As a benefit of this, you can stop a project while others continue to work . Ex: The shipping area can be stopped for maintenance while the concierge continues to operate.
There is a name for this type of development approach: Microservice .
Negative points:
- The complexity of your project will increase . You will have to manipulate login in both, configure two projects in IIS, manipulate DNS, consume more server resources etc.
In my opinion, from the organizational point of view does not change, you have separated them into folders internally.
On performance, we could only be sure of a better performance , if each project is put on a different server .
If they are placed on the same server, only via stress tests and banchmarks we would know. Even so, likely not to make major differences by being on the same server .
It's up to you to analyze the technical strengths and weaknesses and decide what works best for you or your team. If the increase in scalability of the microservice compensates for the increase in the complexity of the system.