My users were experiencing 8-second delays every hour. Here's how I fixed it.

• The Problem: First user after cache expiry = terrible experience
• The Solution: Refresh caches before they expire
• Implementation Time: 2 hours
• Monthly Cost: $1.92
• Impact: Zero cold starts, happy users

The Problem: Every Hour, Someone Suffered

What Was Happening

My cache expired every hour. The unlucky first user after expiry got this:

Timeline of a cold start disaster:
┌─────────────────────────────────────┐
│  11:00:00 - Cache expires           │
│  11:00:01 - User clicks "Generate"  │
│           ↓                         │
│  Create new cache: 2-3 seconds     │
│  Generate response: 3-5 seconds    │
│           ↓                         │
│  Total wait: 5-8 seconds           │
│  User reaction: "Why so slow?"     │
└─────────────────────────────────────┘

Next user at 11:00:15:
┌─────────────────────────────────────┐
│  Cache exists now                  │
│  Generate response: 3-5 seconds    │
│  User reaction: "Nice and fast!"   │
└─────────────────────────────────────┘

The damage:

• 24 cold starts per day (every hour)
• 24 frustrated users
• Inconsistent experience
• Support complaints

The Solution: Warm Caches Before They Expire

Instead of waiting for expiry, refresh 10 minutes early:

Better timeline:
┌─────────────────────────────────────┐
│  10:50 - Cache warmer runs          │
│         (Cache still has 10 min)    │
│  Creates fresh cache in background  │
│           ↓                         │
│  11:00 - Old cache would expire     │
│  But new cache already ready!       │
│           ↓                         │
│  11:00:01 - User clicks "Generate"  │
│  Uses warm cache immediately        │
│  Total wait: 3-5 seconds            │
│  User reaction: "Always fast!"      │
└─────────────────────────────────────┘