diff --git a/.changeset/stale-dryers-sparkle.md b/.changeset/stale-dryers-sparkle.md
new file mode 100644
index 0000000000..50f75e6b3d
--- /dev/null
+++ b/.changeset/stale-dryers-sparkle.md
@@ -0,0 +1,5 @@
+---
+"viem": patch
+---
+
+Improved `.extend` performance with `publicActions` and other large types.
diff --git a/biome.json b/biome.json
index 643990ae08..46d4ef4d7d 100644
--- a/biome.json
+++ b/biome.json
@@ -10,6 +10,7 @@
       ".vercel",
       "**/node_modules",
       "CHANGELOG.md",
+      "bun.lockb",
       "cache",
       "test/contracts",
       "test/kzg/*.json",
diff --git a/src/actions/public/mulitcall.bench-d.ts b/src/actions/public/mulitcall.bench-d.ts
new file mode 100644
index 0000000000..354a2c8ba2
--- /dev/null
+++ b/src/actions/public/mulitcall.bench-d.ts
@@ -0,0 +1,33 @@
+import { bench } from '@arktype/attest'
+
+import {
+  baycContractConfig,
+  usdcContractConfig,
+} from '../../../test/src/abis.js'
+import { anvil } from '../../chains/index.js'
+import { createClient } from '../../clients/createClient.js'
+import { http } from '../../clients/transports/http.js'
+import { multicall } from './multicall.js'
+
+bench('multicall return type', async () => {
+  const client = createClient({ chain: anvil, transport: http() })
+  const res = multicall(client, {
+    allowFailure: false,
+    contracts: [
+      {
+        ...usdcContractConfig,
+        functionName: 'totalSupply',
+      },
+      {
+        ...usdcContractConfig,
+        functionName: 'balanceOf',
+        args: ['0x...'],
+      },
+      {
+        ...baycContractConfig,
+        functionName: 'name',
+      },
+    ],
+  })
+  return {} as typeof res
+}).types([192503, 'instantiations'])
diff --git a/src/actions/public/readContract.bench-d.ts b/src/actions/public/readContract.bench-d.ts
new file mode 100644
index 0000000000..ce0b6c2a06
--- /dev/null
+++ b/src/actions/public/readContract.bench-d.ts
@@ -0,0 +1,17 @@
+import { bench } from '@arktype/attest'
+
+import { usdcContractConfig } from '../../../test/src/abis.js'
+import { anvil } from '../../chains/index.js'
+import { createClient } from '../../clients/createClient.js'
+import { http } from '../../clients/transports/http.js'
+import { readContract } from './readContract.js'
+
+bench('readContract return type', async () => {
+  const client = createClient({ chain: anvil, transport: http() })
+  const res = readContract(client, {
+    ...usdcContractConfig,
+    functionName: 'balanceOf',
+    args: ['0x...'],
+  })
+  return {} as typeof res
+}).types([152288, 'instantiations'])
diff --git a/src/clients/createTestClient.bench-d.ts b/src/clients/createTestClient.bench-d.ts
new file mode 100644
index 0000000000..dfb1d7e2ed
--- /dev/null
+++ b/src/clients/createTestClient.bench-d.ts
@@ -0,0 +1,18 @@
+import { bench } from '@arktype/attest'
+
+import { createClient } from './createClient.js'
+import { createTestClient } from './createTestClient.js'
+import { testActions } from './decorators/test.js'
+import { http } from './transports/http.js'
+
+bench('createTestClient', () => {
+  const client = createTestClient({ mode: 'anvil', transport: http() })
+  return {} as typeof client
+}).types([668, 'instantiations'])
+
+bench('createClient.extend + testActions', () => {
+  const client = createClient({ transport: http() }).extend(
+    testActions({ mode: 'anvil' }),
+  )
+  return {} as typeof client
+}).types([6275, 'instantiations'])