1) You stated something in there about an .iso installer but didn't mention a version. You also have reference to "scratch install", but have not provided a link to the instruction set used. This information is often very useful in understanding your situation.
2) You have mentioned "database load 100%" and "database shows 100% load on web interface" which I presume to mean the value shown when you click on "Reports" and are shown a list of servers. This value is not actually a "load" per se, but a calculation of a value based on an assumed calibrated maximum number of processes. However, this value (when uncalibrated) has zero meaning. Average Server Load, which is available in the CLI, shows the number of cores busy (on average) in the last 1/5/10 minutes. This number should never exceed the actual core count. For safety (peace of mind) it should never really exceed 50% of the core count except perhaps for the occasional peak moment.
3) If you want that "Load" value to show a usable number, you'll need to calibrate the data collection service for it. This, of course, is where the installation method would come in, which is missing.