Experience bad performance IIS 8 200 applications

We are developing an application which is almost ready for launch. We have the vision to host around 200 applications on one server. So we did a loadtest.

When I test with one application and 200 users, no problem at all and seems to work very quick. But the test when having 200 applications and each application one user works very bad. All applications are in one AppPool

We did some optimalisations like:

• minified the css/javascript
• put extra mem (2GB for 200 users and one application, no problem, 200 applications was problem, after that we upgraded to 12GB memory but performance keep bad)
• Set the setting in IIS to release memory when application is not used anymore of idle for a time of 30 min.
• We used interning of .NET

We will do:

• Move static files outside the SSL so can be cached

Do anyone have experience with this (in my opinion small set of applications) set of applications? I expected IIS would use his memory better.