LogsPanel: Speed up labels processing by 50x (#103296)

.betterer.results

@@ -3805,6 +3805,9 @@ exports[`better eslint`] = {
     "public/app/features/logs/components/LogLabelStats.tsx:5381": [
       [0, 0, 0, "No untranslated strings. Wrap text with <Trans />", "0"]
     ],
+    "public/app/features/logs/logsFrame.ts:5381": [
+      [0, 0, 0, "Do not use any type assertions.", "0"]
+    ],
     "public/app/features/logs/utils.ts:5381": [
       [0, 0, 0, "Do not use any type assertions.", "0"]
     ],

public/app/features/logs/logsFrame.ts

@@ -35,14 +35,32 @@ const DATAPLANE_SEVERITY_NAME = 'severity';
 const DATAPLANE_ID_NAME = 'id';
 const DATAPLANE_LABELS_NAME = 'labels';
 
+// NOTE: this is a hot fn, we need to avoid allocating new objects here
 export function logFrameLabelsToLabels(logFrameLabels: LogFrameLabels): Labels {
-  const result: Labels = {};
+  let needsSerialization = false;
 
-  Object.entries(logFrameLabels).forEach(([k, v]) => {
-    result[k] = typeof v === 'string' ? v : JSON.stringify(v);
-  });
+  for (const k in logFrameLabels) {
+    const v = logFrameLabels[k];
 
-  return result;
+    if (typeof v !== 'string') {
+      needsSerialization = true;
+      break;
+    }
+  }
+
+  if (needsSerialization) {
+    let labels: Labels = {};
+
+    for (const k in logFrameLabels) {
+      const v = logFrameLabels[k];
+      labels[k] = typeof v === 'string' ? v : JSON.stringify(v);
+    }
+
+    return labels;
+  }
+
+  // @ts-ignore
+  return logFrameLabels as Labels;
 }
 
 export function parseDataplaneLogsFrame(frame: DataFrame): LogsFrame | null {