measure ws connect time

priv/frontend/src/ws/client.js

@@ -49,13 +49,15 @@ export default class StreamingClient extends NanoEvents {
   }
 
   connect () {
+    const begin = Date.now()
     log('connecting')
 
     const ws = this.ws = new WebSocket(this.url)
     window.ws = ws
 
     ws.onopen = () => {
-      log('connected')
+      const took = Date.now() - begin
+      log(`connected (took ${took}ms)`)
       this.subscribe()
     }