App fails to sync offline changes. Fix: Clear the cache (Settings → Offline → Clear cache) and restart. Ensure your system clock is accurate (NTP-synced).

proton.me/mail/download

| Metric | Web Version (Chrome) | Windows App | |--------|----------------------|--------------| | RAM idle | ~180MB | ~220MB | | RAM with large mailbox | ~350MB | ~310MB | | CPU background sync | 0-1% | 0-2% | | Launch time (cold) | 2.1s (browser first) | 1.3s | | Search speed (10k emails) | 1.2s | 0.9s |

Have you tried the ProtonMail Windows app? Share your experience in the comments below (or securely via Proton Mail, of course).