add per-collector tick timing logs (debug, >5ms threshold)

server/services/collectors/sensors.js

@@ -230,6 +230,7 @@ export class SensorsCollector extends EventEmitter {
   }
 
   _tick() {
+    const t0 = performance.now()
     const ts = Date.now()
     const samples = sampleSensors()
     if (!samples.length) return
@@ -240,6 +241,8 @@ export class SensorsCollector extends EventEmitter {
       values: s.values,
     }))
     this.emit('samples', batch)
+    const dur = performance.now() - t0
+    if (dur > 5) log.debug('tick', { collector: 'sensors', durMs: Math.round(dur * 10) / 10 })
   }
 }