Performance Lab · LAB-05Under investigation
“A smaller bundle is always faster.”
Smaller usually helps, but *when* bytes arrive and *what* they do on arrival matter more than the total.
- Verdict
- PARTLY TRUE
- Level
- SYSTEMS
- Division
- LAB-05
- References
- 02
Investigation
Splitting a 500KB bundle into ten 50KB chunks does not make the page faster if the critical path now needs six of them in sequence. Each additional request on the critical path costs a round trip, and a waterfall of small files can easily lose to one larger file.
| Change | Usually helps | Can backfire |
|---|---|---|
| Remove an unused dependency | Always | |
| Route-level code splitting | Yes | If the split point is on the critical path |
| Component-level splitting | Sometimes | Waterfalls, layout shift on late arrival |
| Inlining critical CSS | Yes for first paint | Uncacheable; bloats every HTML response |
| Deferring all scripts | Yes | Delays hydration if interaction comes early |