The login page should load only the plugins that are absolutely necessary and only when needed

[azasypkin]

Summary

We've recently learned that the login page loads bundles from quite a few plugins, many of which don't seem relevant at all (e.g., spaces, screenshotMode). We should investigate why this is happening and see if we can avoid loading some of them or at least load them lazily.

Should the login page be a separate lightweight plugin?

{
  "url": "http://localhost:5620/login",
  "bundleCount": 25,
  "totalSize": 5309189,
  "pluginCount": 18,
  "plugins": [
    {
      "name": "banners",
      "bundlesCount": 1,
      "totalSize": 12998,
      "bundles": [
        {
          "name": "banners.plugin.js",
          "transferredSize": 12998
        }
      ]
    },
    {
      "name": "cloud",
      "bundlesCount": 1,
      "totalSize": 7391,
      "bundles": [
        {
          "name": "cloud.plugin.js",
          "transferredSize": 7391
        }
      ]
    },
    {
      "name": "core",
      "bundlesCount": 1,
      "totalSize": 343183,
      "bundles": [
        {
          "name": "core.entry.js",
          "transferredSize": 343183
        }
      ]
    },
    {
      "name": "dataViews",
      "bundlesCount": 1,
      "totalSize": 43184,
      "bundles": [
        {
          "name": "dataViews.plugin.js",
          "transferredSize": 43184
        }
      ]
    },
    {
      "name": "esUiShared",
      "bundlesCount": 1,
      "totalSize": 110010,
      "bundles": [
        {
          "name": "esUiShared.plugin.js",
          "transferredSize": 110010
        }
      ]
    },
    {
      "name": "features",
      "bundlesCount": 1,
      "totalSize": 4685,
      "bundles": [
        {
          "name": "features.plugin.js",
          "transferredSize": 4685
        }
      ]
    },
    {
      "name": "kbn-ui-shared-deps-npm",
      "bundlesCount": 5,
      "totalSize": 2843270,
      "bundles": [
        {
          "name": "kbn-ui-shared-deps-npm.chunk.29169.js",
          "transferredSize": 2460
        },
        {
          "name": "kbn-ui-shared-deps-npm.chunk.4191.js",
          "transferredSize": 2325
        },
        {
          "name": "kbn-ui-shared-deps-npm.chunk.89271.js",
          "transferredSize": 3115
        },
        {
          "name": "kbn-ui-shared-deps-npm.chunk.9282.js",
          "transferredSize": 2231
        },
        {
          "name": "kbn-ui-shared-deps-npm.dll.js",
          "transferredSize": 2833139
        }
      ]
    },
    {
      "name": "kbn-ui-shared-deps-src",
      "bundlesCount": 1,
      "totalSize": 1617578,
      "bundles": [
        {
          "name": "kbn-ui-shared-deps-src.js",
          "transferredSize": 1617578
        }
      ]
    },
    {
      "name": "kibanaReact",
      "bundlesCount": 1,
      "totalSize": 44823,
      "bundles": [
        {
          "name": "kibanaReact.plugin.js",
          "transferredSize": 44823
        }
      ]
    },
    {
      "name": "kibanaUtils",
      "bundlesCount": 1,
      "totalSize": 68410,
      "bundles": [
        {
          "name": "kibanaUtils.plugin.js",
          "transferredSize": 68410
        }
      ]
    },
    {
      "name": "licensing",
      "bundlesCount": 1,
      "totalSize": 9874,
      "bundles": [
        {
          "name": "licensing.plugin.js",
          "transferredSize": 9874
        }
      ]
    },
    {
      "name": "mockIdpPlugin",
      "bundlesCount": 1,
      "totalSize": 10450,
      "bundles": [
        {
          "name": "mockIdpPlugin.plugin.js",
          "transferredSize": 10450
        }
      ]
    },
    {
      "name": "remoteClusters",
      "bundlesCount": 1,
      "totalSize": 9730,
      "bundles": [
        {
          "name": "remoteClusters.plugin.js",
          "transferredSize": 9730
        }
      ]
    },
    {
      "name": "screenshotMode",
      "bundlesCount": 1,
      "totalSize": 4800,
      "bundles": [
        {
          "name": "screenshotMode.plugin.js",
          "transferredSize": 4800
        }
      ]
    },
    {
      "name": "security",
      "bundlesCount": 4,
      "totalSize": 118549,
      "bundles": [
        {
          "name": "security.chunk.10.js",
          "transferredSize": 40091
        },
        {
          "name": "security.chunk.13.js",
          "transferredSize": 15982
        },
        {
          "name": "security.chunk.7.js",
          "transferredSize": 7318
        },
        {
          "name": "security.plugin.js",
          "transferredSize": 55158
        }
      ]
    },
    {
      "name": "spaces",
      "bundlesCount": 1,
      "totalSize": 29747,
      "bundles": [
        {
          "name": "spaces.plugin.js",
          "transferredSize": 29747
        }
      ]
    },
    {
      "name": "telemetry",
      "bundlesCount": 1,
      "totalSize": 23780,
      "bundles": [
        {
          "name": "telemetry.plugin.js",
          "transferredSize": 23780
        }
      ]
    },
    {
      "name": "usageCollection",
      "bundlesCount": 1,
      "totalSize": 6727,
      "bundles": [
        {
          "name": "usageCollection.plugin.js",
          "transferredSize": 6727
        }
      ]
    }
  ]
}

[elasticmachine]

Pinging @elastic/kibana-security (Team:Security)