Consider the cost of 3rd party modules. Most will allow a large number or even unlimited portals in a single DNN install. Break it out to multiple installs and your module cost goes way up! This forced me to use multiple portals in one DNN DB.
Advantages:
- One backup gets all portals
- You have one code base and DB to troubleshoot for issues
- Upgrades only have to be done on one code base
Each DNN install is just another 'thing' to maintain and the more ' things' to maintain, the more cost and time you spend
I solved the load time issue by simply running Smarter Ping on my pc and having it ping my site every 5 min. No more load issues, EVER.
I run dozens of portals with thousands of users on one DNN install and it works great.
Also note that every DNN install takes more server memory so plan on a huge server or servers if you want to install lots of DNN instances and DBs.