core-js vs Slimbox
Head-to-head usage across the sites we track.
Top sites by authority
core-js · Slimbox · how many of each technology's sites sit in the web's highest authority tiers
Open Page Rank 9+
243
3
Open Page Rank 8+
5,081
18
Open Page Rank 7+
26,045
33
Open Page Rank 6+
56,582
47
Open Page Rank 5+
107,942
68
Open Page Rank scores 0 to 10 from the open web link graph; 9+ covers only a few hundred domains worldwide.
By country
core-js · Slimbox · share of sites in each country using one or the other
United States
1,320,418
191
India
439,882
111
Brazil
411,231
85
United Kingdom
404,005
132
Germany
391,462
519
France
311,727
182
Canada
298,167
63
Italy
291,018
171
Audience countries from the Chrome UX Report, top markets of either technology.
Real user performance
| Metric | core-js | Slimbox |
|---|---|---|
| LCP | 2 s | 1.4 s |
| INP | 75 ms | 75 ms |
| CLS | 0 | 0 |
| TTFB | 800 ms | 700 ms |
Median site's p75 values from the Chrome UX Report, Aug 2026. Lower is better; green meets Google's "good" threshold. This describes the sites that use each technology, not the technology's own overhead.
Sites that switched
Domains that dropped one technology and adopted the other within about a year, data nobody else gives away free.
core-js to Slimbox
| Domain | When |
|---|---|
| b-pep.com | Mar 2026 |
Slimbox to core-js
| Domain | When |
|---|---|
| tdgrupp.ru | Jul 2026 |
| kkd.hr | Feb 2026 |