perf: diagnoistics improvements

electron/diagnostics/high-memory-alert.rules.ts

@@ -0,0 +1,11 @@
+/** 2 GiB working-set threshold for writing a diagnostics snapshot. */
+export const HIGH_MEMORY_THRESHOLD_KB = 2 * 1024 * 1024;
+
+export function exceedsHighMemoryThreshold(totalWorkingSetKb: number | null | undefined): boolean {
+  return typeof totalWorkingSetKb === 'number'
+    && totalWorkingSetKb >= HIGH_MEMORY_THRESHOLD_KB;
+}
+
+export function formatWorkingSetGb(totalWorkingSetKb: number): string {
+  return (totalWorkingSetKb / (1024 * 1024)).toFixed(2);
+}