diff --git a/buildWorkers.mjs b/buildWorkers.mjs
new file mode 100644
index 00000000..1f1782a5
--- /dev/null
+++ b/buildWorkers.mjs
@@ -0,0 +1,62 @@
+// main worker file intended for computing world geometry is built using prismarine-viewer/buildWorker.mjs
+import { build, context } from 'esbuild'
+import fs from 'fs'
+import { sharedPlugins } from './scripts/esbuildPlugins.mjs'
+
+const watch = process.argv.includes('-w')
+
+const result = await (watch ? context : build)({
+    bundle: true,
+    platform: 'browser',
+    entryPoints: [/* 'prismarine-viewer/examples/webglRendererWorker.ts',  */'src/worldSaveWorker.ts'],
+    outdir: 'prismarine-viewer/public/',
+    sourcemap: watch ? 'inline' : 'external',
+    minify: !watch,
+    treeShaking: true,
+    logLevel: 'info',
+    alias: {
+        'three': './node_modules/three/src/Three.js',
+        events: 'events', // make explicit
+        buffer: 'buffer',
+        'fs': 'browserfs/dist/shims/fs.js',
+        http: 'http-browserify',
+        perf_hooks: './src/perf_hooks_replacement.js',
+        crypto: './src/crypto.js',
+        stream: 'stream-browserify',
+        net: 'net-browserify',
+        assert: 'assert',
+        dns: './src/dns.js'
+    },
+    inject: [
+        './src/shims.js'
+    ],
+    plugins: [
+        {
+            name: 'writeOutput',
+            setup (build) {
+                build.onEnd(({ outputFiles }) => {
+                    for (const file of outputFiles) {
+                        for (const dir of ['prismarine-viewer/public', 'dist']) {
+                            const baseName = file.path.split('/').pop()
+                            fs.writeFileSync(`${dir}/${baseName}`, file.contents)
+                        }
+                    }
+                })
+            }
+        },
+        ...sharedPlugins
+    ],
+    loader: {
+        '.vert': 'text',
+        '.frag': 'text'
+    },
+    mainFields: [
+        'browser', 'module', 'main'
+    ],
+    keepNames: true,
+    write: false,
+})
+
+if (watch) {
+    await result.watch()
+}
diff --git a/scripts/esbuildPlugins.mjs b/scripts/esbuildPlugins.mjs
index e5af5ec8..3be7ba6e 100644
--- a/scripts/esbuildPlugins.mjs
+++ b/scripts/esbuildPlugins.mjs
@@ -18,7 +18,7 @@ const watchExternal = [
 ]
 
 /** @type {import('esbuild').Plugin[]} */
-const plugins = [
+const sharedPlugins = [
   {
     name: 'strict-aliases',
     setup (build) {
@@ -65,6 +65,53 @@ const plugins = [
       })
     }
   },
+  {
+    name: 'fix-dynamic-require',
+    setup (build) {
+      build.onResolve({
+        filter: /1\.14\/chunk/,
+      }, async ({ resolveDir, path }) => {
+        if (!resolveDir.includes('prismarine-provider-anvil')) return
+        return {
+          namespace: 'fix-dynamic-require',
+          path,
+          pluginData: {
+            resolvedPath: `${join(resolveDir, path)}.js`,
+            resolveDir
+          },
+        }
+      })
+      build.onLoad({
+        filter: /.+/,
+        namespace: 'fix-dynamic-require',
+      }, async ({ pluginData: { resolvedPath, resolveDir } }) => {
+        const resolvedFile = await fs.promises.readFile(resolvedPath, 'utf8')
+        return {
+          contents: resolvedFile.replace("require(`prismarine-chunk/src/pc/common/BitArray${noSpan ? 'NoSpan' : ''}`)", "noSpan ? require(`prismarine-chunk/src/pc/common/BitArray`) : require(`prismarine-chunk/src/pc/common/BitArrayNoSpan`)"),
+          resolveDir,
+          loader: 'js',
+        }
+      })
+    }
+  },
+  polyfillNode({
+    polyfills: {
+      fs: false,
+      dns: false,
+      crypto: false,
+      events: false,
+      http: false,
+      stream: false,
+      buffer: false,
+      perf_hooks: false,
+      net: false,
+      assert: false,
+    },
+  })
+]
+
+/** @type {import('esbuild').Plugin[]} */
+const plugins = [
   {
     name: 'data-assets',
     setup (build) {
@@ -256,35 +303,6 @@ const plugins = [
       })
     }
   },
-  {
-    name: 'fix-dynamic-require',
-    setup (build) {
-      build.onResolve({
-        filter: /1\.14\/chunk/,
-      }, async ({ resolveDir, path }) => {
-        if (!resolveDir.includes('prismarine-provider-anvil')) return
-        return {
-          namespace: 'fix-dynamic-require',
-          path,
-          pluginData: {
-            resolvedPath: `${join(resolveDir, path)}.js`,
-            resolveDir
-          },
-        }
-      })
-      build.onLoad({
-        filter: /.+/,
-        namespace: 'fix-dynamic-require',
-      }, async ({ pluginData: { resolvedPath, resolveDir } }) => {
-        const resolvedFile = await fs.promises.readFile(resolvedPath, 'utf8')
-        return {
-          contents: resolvedFile.replace("require(`prismarine-chunk/src/pc/common/BitArray${noSpan ? 'NoSpan' : ''}`)", "noSpan ? require(`prismarine-chunk/src/pc/common/BitArray`) : require(`prismarine-chunk/src/pc/common/BitArrayNoSpan`)"),
-          resolveDir,
-          loader: 'js',
-        }
-      })
-    }
-  },
   {
     name: 'react-displayname',
     setup (build) {
@@ -310,20 +328,7 @@ const plugins = [
       })
     }
   },
-  polyfillNode({
-    polyfills: {
-      fs: false,
-      dns: false,
-      crypto: false,
-      events: false,
-      http: false,
-      stream: false,
-      buffer: false,
-      perf_hooks: false,
-      net: false,
-      assert: false,
-    },
-  })
+  ...sharedPlugins
 ]
 
-export { plugins, connectedClients as clients }
+export { plugins, connectedClients as clients, sharedPlugins }
diff --git a/src/flyingSquidEvents.ts b/src/flyingSquidEvents.ts
index fbab268b..651b2b04 100644
--- a/src/flyingSquidEvents.ts
+++ b/src/flyingSquidEvents.ts
@@ -9,5 +9,38 @@ export default () => {
       chatInputValueGlobal.value = '/warp '
       showModal({ reactType: 'chat' })
     })
-  })
+  });
+
+  (localServer as any).loadChunksOptimized = (chunks) => {
+    const workersNum = 5
+    const workers = [] as Worker[]
+
+    for (let i = 0; i < workersNum; i++) {
+      const worker = new Worker('./worldSaveWorker.js')
+      workers.push(worker)
+    }
+
+    console.time('chunks-main')
+    for (const [i, worker] of workers.entries()) {
+      worker.postMessage({
+        type: 'readChunks',
+        chunks: chunks.slice(i * chunks.length / workersNum, (i + 1) * chunks.length / workersNum),
+        folder: localServer!.options.worldFolder + '/region'
+      })
+    }
+
+    let finishedWorkers = 0
+
+    for (const worker of workers) {
+      // eslint-disable-next-line @typescript-eslint/no-loop-func
+      worker.onmessage = (msg) => {
+        if (msg.data.type === 'done') {
+          finishedWorkers++
+          if (finishedWorkers === workersNum) {
+            console.timeEnd('chunks-main')
+          }
+        }
+      }
+    }
+  }
 }
diff --git a/src/react/IndicatorEffects.tsx b/src/react/IndicatorEffects.tsx
index b767cc23..b9205e23 100644
--- a/src/react/IndicatorEffects.tsx
+++ b/src/react/IndicatorEffects.tsx
@@ -63,7 +63,6 @@ export default ({ indicators, effects }: {indicators: typeof defaultIndicatorsSt
   }, [effects])
 
   useEffect(() => {
-    // todo use more precise timer for each effect
     const interval = setInterval(() => {
       for (const [index, effect] of effectsRef.current.entries()) {
         if (effect.time === 0) {
diff --git a/src/workerWorkaround.ts b/src/workerWorkaround.ts
new file mode 100644
index 00000000..66d6c30f
--- /dev/null
+++ b/src/workerWorkaround.ts
@@ -0,0 +1,3 @@
+global = globalThis
+globalThis.window = globalThis
+window.mcData = {}
diff --git a/src/worldSaveWorker.ts b/src/worldSaveWorker.ts
new file mode 100644
index 00000000..ac8b4b08
--- /dev/null
+++ b/src/worldSaveWorker.ts
@@ -0,0 +1,72 @@
+import './workerWorkaround'
+import fs from 'fs'
+import './fs2'
+import { Anvil } from 'prismarine-provider-anvil'
+import WorldLoader from 'prismarine-world'
+
+import * as browserfs from 'browserfs'
+import { generateSpiralMatrix } from 'flying-squid/dist/utils'
+import '../dist/mc-data/1.14'
+import { oneOf } from '@zardoy/utils'
+
+console.log('install')
+browserfs.install(window)
+window.fs = fs
+
+onmessage = (msg) => {
+  globalThis.readSkylight = false
+  if (msg.data.type === 'readChunks') {
+    browserfs.configure({
+      fs: 'MountableFileSystem',
+      options: {
+        '/data': { fs: 'IndexedDB' },
+      },
+    }, async () => {
+      const version = '1.14.4'
+      const AnvilLoader = Anvil(version)
+      const World = WorldLoader(version)
+      // const folder = '/data/worlds/Greenfield v0.5.3-3/region'
+      const { folder } = msg.data
+      const world = new World(() => {
+        throw new Error('Not implemented')
+      }, new AnvilLoader(folder))
+      // const chunks = generateSpiralMatrix(20)
+      const { chunks } = msg.data
+      // const spawn = {
+      //   x: 113,
+      //   y: 64,
+
+      // }
+      console.log('starting...')
+      console.time('columns')
+      const loadedColumns = [] as any[]
+      const columnToTransfarable = (chunk) => {
+        return {
+          biomes: chunk.biomes,
+          // blockEntities: chunk.blockEntities,
+          // sectionMask: chunk.sectionMask,
+          sections: chunk.sections,
+          // skyLightMask: chunk.skyLightMask,
+          // blockLightMask: chunk.blockLightMask,
+          // skyLightSections: chunk.skyLightSections,
+          // blockLightSections: chunk.blockLightSections
+        }
+      }
+
+      for (const chunk of chunks) {
+        const column = await world.getColumn(chunk[0], chunk[1])
+        if (!column) throw new Error(`Column ${chunk[0]} ${chunk[1]} not found`)
+        postMessage({
+          column: columnToTransfarable(column)
+        })
+      }
+      postMessage({
+        type: 'done',
+      })
+
+      console.timeEnd('columns')
+    })
+  }
+}
+
+// window.fs = fs