TTL configuration in NestJS - Performance & Optimization

Performance: TTL configuration

MEDIUM IMPACT

TTL configuration affects how long cached data stays valid, impacting page load speed and server response times by controlling cache freshness.

Setting cache expiration for API responses

NestJS

cacheManager.set('key', data, { ttl: 60 }); // cache expires after 60 seconds

Cache clears regularly, ensuring fresh data and controlled memory use, improving response speed.

📈 Performance GainReduces server load and memory pressure, improving LCP by serving fresh cached content.

Setting cache expiration for API responses

NestJS

cacheManager.set('key', data, { ttl: 0 }); // no expiration, cache never clears

Cache never expires, causing stale data and increased memory use, slowing server response over time.

📉 Performance CostIncreases memory usage and can block server response, indirectly delaying LCP.

Performance Comparison

Pattern	Cache Freshness	Memory Usage	Server Load	Verdict
No TTL (cache never expires)	Stale data	High	High	[X] Bad
Short TTL (e.g., 60 seconds)	Fresh data	Controlled	Low	[OK] Good

Rendering Pipeline

TTL configuration controls cache validity, affecting whether data is served from cache or requires server processing, influencing the critical rendering path.

→Server Processing

→Network

→Rendering

⚠️ BottleneckServer Processing when cache is stale or missing

Core Web Vital Affected

LCP

TTL configuration affects how long cached data stays valid, impacting page load speed and server response times by controlling cache freshness.

Optimization Tips

1Set TTL to balance data freshness and cache hit rate.

2Avoid TTL=0 to prevent stale data and memory bloat.

3Use TTL to reduce server processing and improve LCP.

Performance Quiz - 3 Questions

How does setting a proper TTL value affect server response times?

A It reduces server processing by serving cached data when valid.

B It increases server load by forcing frequent cache refreshes.

C It has no impact on server response times.

D It always causes stale data to be served.

DevTools: Network

How to check: Open DevTools > Network tab, inspect API response headers for cache-control or custom TTL headers, and observe response times.

What to look for: Look for cache hits vs misses and response time improvements indicating effective TTL usage.