Homogenize prod-app and failover-app differences

Currently, prod-app seems to perform considerably better than failover-app.
The load balancer indicates indeed it is performing less requests and we see the monitoring script acting. Considering that the servers have same hardware and same software, this appears to be wrong.

As a result we should look for differences and choose the most optimized variant.
Differences may appear in the appserv configuration (e.g. the ram), the disks, the network , and maybe even the simplest environment (e.g. the user appserv on failover-app has bash).