{
"measuredAt": "2026-08-17T05:54:35.423Z",
"question": "Does recover the discovery penalty when the image is genuinely hidden?",
"preloadHint": "",
"image": {
"file": "img/hero.jpg",
"width": 1600,
"height": 900,
"quality": 40,
"bytes": 148675,
"kb": 145,
"encoder": "mozjpeg via sharp 0.35.1"
},
"conditions": {
"network": {
"name": "Slow 4G (DevTools preset)",
"downloadKbps": 1638.4,
"uploadKbps": 675,
"latencyMs": 150
},
"cpuThrottling": "4x",
"viewport": {
"width": 412,
"height": 823,
"deviceScaleFactor": 1.75,
"isMobile": true,
"hasTouch": true
},
"runsPerPage": 9,
"coldCache": true,
"interleaved": true,
"headless": true,
"chrome": "Google Chrome for Testing 150.0.7871.24",
"machine": {
"cpu": "Apple M5",
"cores": 10,
"memGB": 16,
"platform": "darwin 25.5.0 arm64",
"node": "v24.16.0"
}
},
"results": [
{
"id": "server-img",
"variant": "server-img",
"label": "Server-rendered ![]()
",
"hidden": false,
"preload": false,
"path": "/server-img.html",
"lcp": {
"n": 9,
"min": 1056,
"median": 1056,
"max": 1060,
"mean": 1057.8,
"stddev": 2.1,
"spread": 4,
"values": [
1060,
1060,
1060,
1060,
1056,
1056,
1056,
1056,
1056
]
},
"phases": {
"ttfb": {
"n": 9,
"min": 0.7,
"median": 0.9,
"max": 2.8,
"mean": 1.1,
"stddev": 0.6,
"spread": 2.1,
"values": [
2.8,
0.9,
0.7,
1.1,
0.9,
1.2,
0.8,
1,
0.9
]
},
"resourceLoadDelay": {
"n": 9,
"min": 162.6,
"median": 164.7,
"max": 165.6,
"mean": 164.5,
"stddev": 0.9,
"spread": 3,
"values": [
162.6,
165.1,
164.7,
165.3,
164.1,
164.4,
165.6,
164.1,
164.8
]
},
"resourceLoadTime": {
"n": 9,
"min": 866.8,
"median": 868.4,
"max": 869.1,
"mean": 868.3,
"stddev": 0.7,
"spread": 2.3,
"values": [
868.9,
868.1,
868.4,
866.8,
869.1,
868.3,
867.9,
869,
868.6
]
},
"elementRenderDelay": {
"n": 9,
"min": 21.7,
"median": 22.1,
"max": 26.8,
"mean": 23.8,
"stddev": 2.3,
"spread": 5.1,
"values": [
25.7,
25.9,
26.2,
26.8,
21.9,
22.1,
21.7,
21.9,
21.7
]
}
},
"requestCount": 5,
"transferBytes": {
"n": 9,
"min": 153119,
"median": 153119,
"max": 153302,
"mean": 153139,
"stddev": 61,
"spread": 183,
"values": [
153302,
153119,
153119,
153119,
153119,
153119,
153119,
153119,
153119
]
}
},
{
"id": "server-img--preload",
"variant": "server-img",
"label": "Server-rendered ![]()
",
"hidden": false,
"preload": true,
"path": "/server-img--preload.html",
"lcp": {
"n": 9,
"min": 1052,
"median": 1056,
"max": 1060,
"mean": 1056.4,
"stddev": 3.1,
"spread": 8,
"values": [
1056,
1060,
1056,
1052,
1056,
1052,
1060,
1060,
1056
]
},
"phases": {
"ttfb": {
"n": 9,
"min": 0.7,
"median": 0.9,
"max": 1.1,
"mean": 0.9,
"stddev": 0.1,
"spread": 0.4,
"values": [
1.1,
0.7,
0.7,
0.9,
0.8,
1,
1,
0.9,
0.8
]
},
"resourceLoadDelay": {
"n": 9,
"min": 162.3,
"median": 164.2,
"max": 165.1,
"mean": 164.1,
"stddev": 0.8,
"spread": 2.8,
"values": [
164.2,
164.6,
162.3,
163.7,
164.1,
165.1,
164.5,
164.2,
164.3
]
},
"resourceLoadTime": {
"n": 9,
"min": 868.1,
"median": 868.8,
"max": 869.7,
"mean": 868.8,
"stddev": 0.5,
"spread": 1.6,
"values": [
868.8,
868.1,
868.7,
869.7,
869.2,
868.2,
868.7,
869.1,
869
]
},
"elementRenderDelay": {
"n": 9,
"min": 17.7,
"median": 21.9,
"max": 26.6,
"mean": 22.6,
"stddev": 3.3,
"spread": 8.9,
"values": [
21.9,
26.6,
24.3,
17.7,
21.9,
17.7,
25.8,
25.8,
21.9
]
}
},
"requestCount": 4,
"transferBytes": {
"n": 9,
"min": 153225,
"median": 153225,
"max": 153225,
"mean": 153225,
"stddev": 0,
"spread": 0,
"values": [
153225,
153225,
153225,
153225,
153225,
153225,
153225,
153225,
153225
]
}
},
{
"id": "lazy",
"variant": "lazy",
"label": "loading=\"lazy\"",
"hidden": true,
"preload": false,
"path": "/lazy.html",
"lcp": {
"n": 9,
"min": 1216,
"median": 1224,
"max": 1236,
"mean": 1224.9,
"stddev": 5.2,
"spread": 20,
"values": [
1228,
1224,
1216,
1236,
1224,
1224,
1224,
1224,
1224
]
},
"phases": {
"ttfb": {
"n": 9,
"min": 0.7,
"median": 0.9,
"max": 1.2,
"mean": 0.9,
"stddev": 0.2,
"spread": 0.5,
"values": [
0.9,
0.7,
1,
0.9,
0.7,
1.2,
0.9,
1,
1
]
},
"resourceLoadDelay": {
"n": 9,
"min": 336.6,
"median": 337.7,
"max": 348.4,
"mean": 339,
"stddev": 3.7,
"spread": 11.8,
"values": [
340.1,
337.7,
337.4,
348.4,
338.8,
337.2,
338.2,
337,
336.6
]
},
"resourceLoadTime": {
"n": 9,
"min": 859.3,
"median": 860.3,
"max": 866.7,
"mean": 861.2,
"stddev": 2.4,
"spread": 7.4,
"values": [
859.7,
860.3,
860.1,
863.2,
859.3,
859.5,
866.7,
860.7,
861.1
]
},
"elementRenderDelay": {
"n": 9,
"min": 17.5,
"median": 25.3,
"max": 27.3,
"mean": 23.7,
"stddev": 3.5,
"spread": 9.8,
"values": [
27.3,
25.3,
17.5,
23.5,
25.2,
26.1,
18.2,
25.3,
25.3
]
}
},
"requestCount": 4,
"transferBytes": {
"n": 9,
"min": 153137,
"median": 153137,
"max": 153137,
"mean": 153137,
"stddev": 0,
"spread": 0,
"values": [
153137,
153137,
153137,
153137,
153137,
153137,
153137,
153137,
153137
]
}
},
{
"id": "lazy--preload",
"variant": "lazy",
"label": "loading=\"lazy\"",
"hidden": true,
"preload": true,
"path": "/lazy--preload.html",
"lcp": {
"n": 9,
"min": 1056,
"median": 1056,
"max": 1060,
"mean": 1056.4,
"stddev": 1.3,
"spread": 4,
"values": [
1056,
1056,
1056,
1056,
1060,
1056,
1056,
1056,
1056
]
},
"phases": {
"ttfb": {
"n": 9,
"min": 0.8,
"median": 0.9,
"max": 1.5,
"mean": 1,
"stddev": 0.2,
"spread": 0.7,
"values": [
0.8,
0.9,
0.8,
0.8,
0.8,
0.9,
1.1,
1,
1.5
]
},
"resourceLoadDelay": {
"n": 9,
"min": 162.6,
"median": 164.3,
"max": 165.3,
"mean": 164.1,
"stddev": 0.8,
"spread": 2.7,
"values": [
163.3,
163.8,
164.3,
165.3,
164.7,
164.3,
163.7,
164.5,
162.6
]
},
"resourceLoadTime": {
"n": 9,
"min": 867.4,
"median": 869.1,
"max": 870.2,
"mean": 869,
"stddev": 0.9,
"spread": 2.8,
"values": [
869.8,
869.4,
869.2,
867.4,
868,
869.1,
869,
868.8,
870.2
]
},
"elementRenderDelay": {
"n": 9,
"min": 21.7,
"median": 21.9,
"max": 26.5,
"mean": 22.4,
"stddev": 1.5,
"spread": 4.8,
"values": [
22.1,
21.9,
21.7,
22.5,
26.5,
21.7,
22.2,
21.7,
21.7
]
}
},
"requestCount": 4,
"transferBytes": {
"n": 9,
"min": 153243,
"median": 153243,
"max": 153243,
"mean": 153243,
"stddev": 0,
"spread": 0,
"values": [
153243,
153243,
153243,
153243,
153243,
153243,
153243,
153243,
153243
]
}
},
{
"id": "css-background",
"variant": "css-background",
"label": "CSS background-image",
"hidden": true,
"preload": false,
"path": "/css-background.html",
"lcp": {
"n": 9,
"min": 1216,
"median": 1216,
"max": 1220,
"mean": 1216.9,
"stddev": 1.8,
"spread": 4,
"values": [
1220,
1216,
1220,
1216,
1216,
1216,
1216,
1216,
1216
]
},
"phases": {
"ttfb": {
"n": 9,
"min": 0.7,
"median": 0.9,
"max": 1.2,
"mean": 0.9,
"stddev": 0.2,
"spread": 0.5,
"values": [
0.9,
0.7,
1.1,
0.8,
0.7,
1.1,
1.2,
1,
0.7
]
},
"resourceLoadDelay": {
"n": 9,
"min": 325.6,
"median": 326.5,
"max": 327.1,
"mean": 326.5,
"stddev": 0.5,
"spread": 1.5,
"values": [
327,
326.7,
325.6,
326.5,
326.4,
327.1,
326.3,
326.1,
326.8
]
},
"resourceLoadTime": {
"n": 9,
"min": 863.5,
"median": 864,
"max": 865,
"mean": 864,
"stddev": 0.5,
"spread": 1.5,
"values": [
863.6,
863.6,
865,
864.2,
864,
863.5,
863.8,
864.5,
864
]
},
"elementRenderDelay": {
"n": 9,
"min": 24.3,
"median": 24.7,
"max": 28.5,
"mean": 25.5,
"stddev": 1.7,
"spread": 4.2,
"values": [
28.5,
25,
28.3,
24.5,
24.9,
24.3,
24.7,
24.4,
24.5
]
}
},
"requestCount": 5,
"transferBytes": {
"n": 9,
"min": 153461,
"median": 153461,
"max": 153461,
"mean": 153461,
"stddev": 0,
"spread": 0,
"values": [
153461,
153461,
153461,
153461,
153461,
153461,
153461,
153461,
153461
]
}
},
{
"id": "css-background--preload",
"variant": "css-background",
"label": "CSS background-image",
"hidden": true,
"preload": true,
"path": "/css-background--preload.html",
"lcp": {
"n": 9,
"min": 1060,
"median": 1064,
"max": 1072,
"mean": 1064.4,
"stddev": 3.7,
"spread": 12,
"values": [
1064,
1064,
1060,
1072,
1068,
1064,
1060,
1064,
1064
]
},
"phases": {
"ttfb": {
"n": 9,
"min": 0.8,
"median": 0.9,
"max": 1.4,
"mean": 1,
"stddev": 0.2,
"spread": 0.6,
"values": [
0.8,
0.8,
1,
0.8,
1.4,
0.9,
1,
1,
0.9
]
},
"resourceLoadDelay": {
"n": 9,
"min": 164.1,
"median": 164.8,
"max": 165.6,
"mean": 164.8,
"stddev": 0.5,
"spread": 1.5,
"values": [
164.7,
164.1,
164.3,
165.2,
164.5,
165.4,
165.6,
165,
164.8
]
},
"resourceLoadTime": {
"n": 9,
"min": 874.7,
"median": 875.3,
"max": 876.3,
"mean": 875.4,
"stddev": 0.6,
"spread": 1.6,
"values": [
875.8,
876.3,
876.1,
875,
875.5,
874.8,
874.7,
874.8,
875.3
]
},
"elementRenderDelay": {
"n": 9,
"min": 18.6,
"median": 22.9,
"max": 31,
"mean": 23.3,
"stddev": 3.8,
"spread": 12.4,
"values": [
22.7,
22.8,
18.6,
31,
26.6,
22.9,
18.7,
23.2,
23
]
}
},
"requestCount": 5,
"transferBytes": {
"n": 9,
"min": 153567,
"median": 153567,
"max": 153567,
"mean": 153567,
"stddev": 0,
"spread": 0,
"values": [
153567,
153567,
153567,
153567,
153567,
153567,
153567,
153567,
153567
]
}
},
{
"id": "client-island",
"variant": "client-island",
"label": "Client-rendered ![]()
",
"hidden": true,
"preload": false,
"path": "/client-island.html",
"lcp": {
"n": 9,
"min": 1220,
"median": 1228,
"max": 1232,
"mean": 1226.7,
"stddev": 4.9,
"spread": 12,
"values": [
1228,
1228,
1232,
1220,
1224,
1224,
1232,
1232,
1220
]
},
"phases": {
"ttfb": {
"n": 9,
"min": 0.7,
"median": 0.8,
"max": 1.1,
"mean": 0.9,
"stddev": 0.2,
"spread": 0.4,
"values": [
1.1,
0.8,
0.8,
0.7,
0.7,
0.7,
1.1,
0.7,
1.1
]
},
"resourceLoadDelay": {
"n": 9,
"min": 337.2,
"median": 338.5,
"max": 340.7,
"mean": 338.8,
"stddev": 1.3,
"spread": 3.5,
"values": [
340.7,
338.4,
338.8,
338,
340.4,
337.5,
338.5,
340.1,
337.2
]
},
"resourceLoadTime": {
"n": 9,
"min": 859.6,
"median": 864.9,
"max": 866.8,
"mean": 864,
"stddev": 2.9,
"spread": 7.2,
"values": [
866.8,
866.6,
865.7,
859.6,
864.8,
860.6,
866.3,
864.9,
860.3
]
},
"elementRenderDelay": {
"n": 9,
"min": 18.1,
"median": 22.2,
"max": 26.7,
"mean": 23,
"stddev": 3.2,
"spread": 8.6,
"values": [
19.4,
22.2,
26.7,
21.7,
18.1,
25.2,
26.1,
26.3,
21.4
]
}
},
"requestCount": 5,
"transferBytes": {
"n": 9,
"min": 153459,
"median": 153459,
"max": 153459,
"mean": 153459,
"stddev": 0,
"spread": 0,
"values": [
153459,
153459,
153459,
153459,
153459,
153459,
153459,
153459,
153459
]
}
},
{
"id": "client-island--preload",
"variant": "client-island",
"label": "Client-rendered ![]()
",
"hidden": true,
"preload": true,
"path": "/client-island--preload.html",
"lcp": {
"n": 9,
"min": 1064,
"median": 1064,
"max": 1072,
"mean": 1065.8,
"stddev": 2.9,
"spread": 8,
"values": [
1072,
1068,
1068,
1064,
1064,
1064,
1064,
1064,
1064
]
},
"phases": {
"ttfb": {
"n": 9,
"min": 0.7,
"median": 0.9,
"max": 1.1,
"mean": 0.9,
"stddev": 0.2,
"spread": 0.4,
"values": [
1,
0.9,
0.8,
0.7,
1.1,
1.1,
1.1,
0.8,
0.8
]
},
"resourceLoadDelay": {
"n": 9,
"min": 163.9,
"median": 164.6,
"max": 169.3,
"mean": 165,
"stddev": 1.6,
"spread": 5.4,
"values": [
169.3,
164.3,
164.7,
164.9,
164.5,
164.6,
163.9,
164.7,
164.5
]
},
"resourceLoadTime": {
"n": 9,
"min": 875,
"median": 875.8,
"max": 876.3,
"mean": 875.6,
"stddev": 0.5,
"spread": 1.3,
"values": [
875,
875.6,
875.9,
875.8,
875,
875.8,
876.3,
875.1,
876
]
},
"elementRenderDelay": {
"n": 9,
"min": 22.5,
"median": 23.4,
"max": 27.2,
"mean": 24.2,
"stddev": 2,
"spread": 4.7,
"values": [
26.7,
27.2,
26.6,
22.6,
23.4,
22.5,
22.7,
23.4,
22.7
]
}
},
"requestCount": 5,
"transferBytes": {
"n": 9,
"min": 153565,
"median": 153565,
"max": 153565,
"mean": 153565,
"stddev": 0,
"spread": 0,
"values": [
153565,
153565,
153565,
153565,
153565,
153565,
153565,
153565,
153565
]
}
}
],
"effects": [
{
"variant": "server-img",
"label": "Server-rendered ![]()
",
"hidden": false,
"lcpWithout": 1056,
"lcpWith": 1056,
"lcpDelta": 0,
"loadDelayWithout": 164.7,
"loadDelayWith": 164.2,
"loadDelayDelta": -0.5,
"verdict": {
"delta": 0,
"deltaPct": 0,
"noiseBand": 8,
"overlap": true,
"verdict": "within noise (runs overlap; widest spread 8)"
}
},
{
"variant": "lazy",
"label": "loading=\"lazy\"",
"hidden": true,
"lcpWithout": 1224,
"lcpWith": 1056,
"lcpDelta": -168,
"loadDelayWithout": 337.7,
"loadDelayWith": 164.3,
"loadDelayDelta": -173.4,
"verdict": {
"delta": -168,
"deltaPct": -13.7,
"noiseBand": 20,
"overlap": false,
"verdict": "separated (no overlap between 1216-1236 and 1056-1060)"
}
},
{
"variant": "css-background",
"label": "CSS background-image",
"hidden": true,
"lcpWithout": 1216,
"lcpWith": 1064,
"lcpDelta": -152,
"loadDelayWithout": 326.5,
"loadDelayWith": 164.8,
"loadDelayDelta": -161.7,
"verdict": {
"delta": -152,
"deltaPct": -12.5,
"noiseBand": 12,
"overlap": false,
"verdict": "separated (no overlap between 1216-1220 and 1060-1072)"
}
},
{
"variant": "client-island",
"label": "Client-rendered ![]()
",
"hidden": true,
"lcpWithout": 1228,
"lcpWith": 1064,
"lcpDelta": -164,
"loadDelayWithout": 338.5,
"loadDelayWith": 164.6,
"loadDelayDelta": -173.9,
"verdict": {
"delta": -164,
"deltaPct": -13.4,
"noiseBand": 12,
"overlap": false,
"verdict": "separated (no overlap between 1220-1232 and 1064-1072)"
}
}
],
"wallClockSeconds": 159
}