Monitoring
Three places to look, none of them noisy.
The Performance app
Open Performance on an operator's computer. It graphs the whole-screen tick time over 10 minutes, an hour or a day, with the screens doing the work, each app's share and the map traffic. Apps are ranked by p99, and each figure is given as p50, p99 and p99.9. The history survives a restart.
The slow-screen line
When the screens run slow, the server logs one line for the run, naming the worst app. No line means the screens have not been a sustained cost; a single spike does not write one.
Optional logging
/computer logging lists the log topics (screens, viewers, frames and chat), all off at startup. /computer logging <topic> on|off turns one on while you chase a problem; the setting lasts until restart.