Pros and cons of having dedicated application pools over keeping web applications in one default app pool

Question

What are pros and cons of having dedicated application pools over keeping web applications in one default app pool?

Answer 1

If you have separate apppools then you pay a penalty in the initial load time of the first person to visit your site and spin back up the apppool after it recycles.

For example let's say overnight no-one hits your server, IIS will spin down (default 20mins I believe). The first person to visit the server will suffer a delay until the your application has been loaded back into memory.

Depending on how you deploy your site (e.g. release mode etc..) this will either not be a problem or could be annoying.

This is why we are looking into moving to a single apppool/server rather than 1 for each site.