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/.github/pull_request_template.md b/.github/pull_request_template.md
index ac05d789b5..5a6f3496e7 100644
--- a/.github/pull_request_template.md
+++ b/.github/pull_request_template.md
@@ -1,5 +1,3 @@
-### Description
-
 <!-- What is this PR solving? Write a clear description or reference the issues it solves (e.g. `fixes #123`). What other alternatives have you explored? Are there any parts you think require more attention from reviewers? -->
 
 <!----------------------------------------------------------------------
diff --git a/.github/workflows/verify.yml b/.github/workflows/verify.yml
index e917027c24..405bba4662 100644
--- a/.github/workflows/verify.yml
+++ b/.github/workflows/verify.yml
@@ -54,7 +54,7 @@ jobs:
     timeout-minutes: 5
     strategy:
       matrix:
-        typescript-version: ['5.3.2', 'latest']
+        version: ['5.3.3', '5.4.5']
 
     steps:
       - name: Clone repository
@@ -65,7 +65,7 @@ jobs:
       - name: Install dependencies
         uses: ./.github/actions/install-dependencies
 
-      - run: bun i -d typescript@${{ matrix.typescript-version }}
+      - run: bun i -d typescript@${{ matrix.version }}
 
       - name: Build contracts
         shell: bash
@@ -74,10 +74,15 @@ jobs:
       - name: Check types
         run: bun run typecheck
 
-      - name: Test types
-        run: bun run test:typecheck
-        env:
-          VITE_ANVIL_BLOCK_NUMBER: ${{ vars.VITE_ANVIL_BLOCK_NUMBER }}
+      - name: Bench types
+        run: bun run typebench
+
+      # Redundant with `pnpm typecheck`
+      # If Vitest adds special features in the future, e.g. type coverage, can add this back!
+      # - name: Test types
+      #   run: bun run test:typecheck
+      #   env:
+      #     VITE_ANVIL_BLOCK_NUMBER: ${{ vars.VITE_ANVIL_BLOCK_NUMBER }}
 
   test:
     name: Test
@@ -211,7 +216,7 @@ jobs:
     timeout-minutes: 10
     strategy:
       matrix:
-        typescript-version: ['5.4.2', 'latest']
+        typescript-version: ['5.4.5']
 
     steps:
       - name: Clone repository
diff --git a/.gitignore b/.gitignore
index 065ccfc36e..d0978172f5 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,6 +3,7 @@ _esm
 _types
 *.local
 .DS_Store
+.attest
 .eslintcache
 .next
 bench
diff --git a/.size-limit.json b/.size-limit.json
index ec19feaf3b..9fd21d0510 100644
--- a/.size-limit.json
+++ b/.size-limit.json
@@ -69,5 +69,17 @@
     "path": "./src/_esm/ens/index.js",
     "limit": "19 kB",
     "import": "{ getEnsAvatar }"
+  },
+  {
+    "name": "viem/siwe",
+    "path": "./src/_esm/siwe/index.js",
+    "limit": "28 kB",
+    "import": "*"
+  },
+  {
+    "name": "viem/siwe (tree-shaking)",
+    "path": "./src/_esm/siwe/index.js",
+    "limit": "27 kB",
+    "import": "{ verifySiweMessage }"
   }
 ]
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/bun.lockb b/bun.lockb
index dd81a98108..45d2448f54 100755
Binary files a/bun.lockb and b/bun.lockb differ
diff --git a/package.json b/package.json
index 924952d8dd..fbb5ddd522 100644
--- a/package.json
+++ b/package.json
@@ -38,14 +38,14 @@
     "test:env:vite": "cd environments/vite && bun run test",
     "test:typecheck": "SKIP_GLOBAL_SETUP=true vitest --typecheck.only -c ./test/vitest.config.ts",
     "test:ui": "vitest dev -c ./test/vitest.config.ts --ui",
+    "typebench": "tsx test/typebench.ts --benchPercentThreshold 10 --benchErrorOnThresholdExceeded",
     "typecheck": "tsc --noEmit",
     "vectors": "bun test vectors/**/*.test.ts",
     "vectors:generate": "bun vectors/generate.ts",
     "version:update": "bun scripts/updateVersion.ts"
   },
   "devDependencies": {
-    "@actions/core": "^1.10.0",
-    "@actions/github": "^5.1.1",
+    "@arktype/attest": "0.7.5",
     "@biomejs/biome": "^1.7.3",
     "@changesets/changelog-github": "^0.4.5",
     "@changesets/cli": "^2.23.2",
@@ -63,6 +63,7 @@
     "rimraf": "^4.4.1",
     "simple-git-hooks": "^2.8.1",
     "size-limit": "^11.1.2",
+    "tsx": "^4.11.0",
     "typescript": "5.4.2",
     "vite": "^5.0.7",
     "vitest": "^1.0.4"
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/multicall.test-d.ts b/src/actions/public/multicall.test-d.ts
index 3138502368..463d2e63f1 100644
--- a/src/actions/public/multicall.test-d.ts
+++ b/src/actions/public/multicall.test-d.ts
@@ -344,7 +344,6 @@ test('MulticallParameters', async () => {
       | readonly [`0x${string}`]
       | readonly [`0x${string}`, `0x${string}`]
       | undefined
-    value?: undefined
   }>()
 })
 
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/createPublicClient.bench-d.ts b/src/clients/createPublicClient.bench-d.ts
new file mode 100644
index 0000000000..160b159d80
--- /dev/null
+++ b/src/clients/createPublicClient.bench-d.ts
@@ -0,0 +1,16 @@
+import { bench } from '@arktype/attest'
+
+import { createClient } from './createClient.js'
+import { createPublicClient } from './createPublicClient.js'
+import { publicActions } from './decorators/public.js'
+import { http } from './transports/http.js'
+
+bench('createPublicClient', () => {
+  const client = createPublicClient({ transport: http() })
+  return {} as typeof client
+}).types([13470, 'instantiations'])
+
+bench('createClient.extend + publicActions', () => {
+  const client = createClient({ transport: http() }).extend(publicActions)
+  return {} as typeof client
+}).types([246356, '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'])
diff --git a/src/clients/createWalletClient.bench-d.ts b/src/clients/createWalletClient.bench-d.ts
new file mode 100644
index 0000000000..6cfe9e18e1
--- /dev/null
+++ b/src/clients/createWalletClient.bench-d.ts
@@ -0,0 +1,16 @@
+import { bench } from '@arktype/attest'
+
+import { createClient } from './createClient.js'
+import { createWalletClient } from './createWalletClient.js'
+import { walletActions } from './decorators/wallet.js'
+import { http } from './transports/http.js'
+
+bench('createWalletClient', () => {
+  const client = createWalletClient({ transport: http() })
+  return {} as typeof client
+}).types([1384, 'instantiations'])
+
+bench('createClient.extend + walletActions', () => {
+  const client = createClient({ transport: http() }).extend(walletActions)
+  return {} as typeof client
+}).types([193153, 'instantiations'])
diff --git a/src/experimental/eip5792/actions/writeContracts.ts b/src/experimental/eip5792/actions/writeContracts.ts
index 832b227ab5..2721e3e90c 100644
--- a/src/experimental/eip5792/actions/writeContracts.ts
+++ b/src/experimental/eip5792/actions/writeContracts.ts
@@ -1,11 +1,17 @@
-import type { AbiStateMutability, Narrow } from 'abitype'
+import type { Abi, AbiStateMutability, Address, Narrow } from 'abitype'
 
 import type { Client } from '../../../clients/createClient.js'
 import type { Transport } from '../../../clients/transports/createTransport.js'
 import type { ErrorType } from '../../../errors/utils.js'
 import type { Account, GetAccountParameter } from '../../../types/account.js'
 import type { Chain, GetChainParameter } from '../../../types/chain.js'
-import type { ContractFunctionParameters } from '../../../types/contract.js'
+import type {
+  ContractFunctionArgs,
+  ContractFunctionName,
+  GetValue,
+  UnionWiden,
+  Widen,
+} from '../../../types/contract.js'
 import type { MulticallContracts } from '../../../types/multicall.js'
 import {
   type EncodeFunctionDataErrorType,
@@ -19,7 +25,8 @@ import {
 } from './sendCalls.js'
 
 export type WriteContractsParameters<
-  contracts extends readonly unknown[] = readonly ContractFunctionParameters[],
+  contracts extends
+    readonly unknown[] = readonly WriteContractFunctionParameters[],
   chain extends Chain | undefined = Chain | undefined,
   account extends Account | undefined = Account | undefined,
   chainOverride extends Chain | undefined = Chain | undefined,
@@ -98,7 +105,7 @@ export async function writeContracts<
     chainOverride
   >,
 ): Promise<WriteContractsReturnType> {
-  const contracts = parameters.contracts as ContractFunctionParameters[]
+  const contracts = parameters.contracts as WriteContractFunctionParameters[]
   const calls = contracts.map((contract) => {
     const { address, abi, functionName, args, value } = contract
     return {
@@ -113,3 +120,30 @@ export async function writeContracts<
   })
   return sendCalls(client, { ...parameters, calls } as SendCallsParameters)
 }
+
+export type WriteContractFunctionParameters<
+  abi extends Abi | readonly unknown[] = Abi,
+  mutability extends AbiStateMutability = AbiStateMutability,
+  functionName extends ContractFunctionName<
+    abi,
+    mutability
+  > = ContractFunctionName<abi, mutability>,
+  args extends ContractFunctionArgs<
+    abi,
+    mutability,
+    functionName
+  > = ContractFunctionArgs<abi, mutability, functionName>,
+  ///
+  allFunctionNames = ContractFunctionName<abi, mutability>,
+  allArgs = ContractFunctionArgs<abi, mutability, functionName>,
+  // when `args` is inferred to `readonly []` ("inputs": []) or `never` (`abi` declared as `Abi` or not inferrable), allow `args` to be optional.
+  // important that both branches return same structural type
+> = {
+  address: Address
+  abi: abi
+  functionName:
+    | allFunctionNames // show all options
+    | (functionName extends allFunctionNames ? functionName : never) // infer value
+  args?: (abi extends Abi ? UnionWiden<args> : never) | allArgs | undefined
+} & (readonly [] extends allArgs ? {} : { args: Widen<args> }) &
+  GetValue<abi, functionName>
diff --git a/src/experimental/index.ts b/src/experimental/index.ts
index 568c6cbb4c..b7111c5b09 100644
--- a/src/experimental/index.ts
+++ b/src/experimental/index.ts
@@ -27,6 +27,7 @@ export {
   type WriteContractsErrorType,
   type WriteContractsParameters,
   type WriteContractsReturnType,
+  type WriteContractFunctionParameters,
   writeContracts,
 } from './eip5792/actions/writeContracts.js'
 export {
diff --git a/src/jsr.json b/src/jsr.json
index 2ea96dd74e..1b3bd577dd 100644
--- a/src/jsr.json
+++ b/src/jsr.json
@@ -17,6 +17,11 @@
   },
   "publish": {
     "include": ["LICENSE", "README.md", "CHANGELOG.md", "**/*.ts"],
-    "exclude": ["**/*.bench.ts", "**/*.test.ts", "**/*.test-d.ts"]
+    "exclude": [
+      "**/*.bench.ts",
+      "**/*.bench-d.ts",
+      "**/*.test.ts",
+      "**/*.test-d.ts"
+    ]
   }
 }
diff --git a/src/package.json b/src/package.json
index a3c4af556d..a6e342f035 100644
--- a/src/package.json
+++ b/src/package.json
@@ -10,11 +10,12 @@
   "sideEffects": false,
   "files": [
     "*",
-    "!**/*.tsbuildinfo",
+    "!**/*.bench.ts",
+    "!**/*.bench-d.ts",
     "!**/*.test.ts",
     "!**/*.test.ts.snap",
     "!**/*.test-d.ts",
-    "!**/*.bench.ts",
+    "!**/*.tsbuildinfo",
     "!tsconfig.build.json",
     "!jsr.json"
   ],
diff --git a/src/types/contract.ts b/src/types/contract.ts
index bb8f5b13b6..9dc276df54 100644
--- a/src/types/contract.ts
+++ b/src/types/contract.ts
@@ -209,9 +209,7 @@ export type ContractFunctionParameters<
     | allFunctionNames // show all options
     | (functionName extends allFunctionNames ? functionName : never) // infer value
   args?: (abi extends Abi ? UnionWiden<args> : never) | allArgs | undefined
-} & (readonly [] extends allArgs ? {} : { args: Widen<args> }) &
-  // TODO: Remove `GetValue` from here (should be applied to top-level type as separate utility)
-  GetValue<abi, functionName>
+} & (readonly [] extends allArgs ? {} : { args: Widen<args> })
 
 export type ContractFunctionReturnType<
   abi extends Abi | readonly unknown[] = Abi,
diff --git a/test/typebench.ts b/test/typebench.ts
new file mode 100644
index 0000000000..d312d98b63
--- /dev/null
+++ b/test/typebench.ts
@@ -0,0 +1,7 @@
+import { globby } from 'globby'
+import { tsImport } from 'tsx/esm/api'
+
+const paths = await globby(['src/**/*.bench-d.ts'])
+for (const path of paths) {
+  await tsImport(`../${path}`, import.meta.url)
+}
diff --git a/tsconfig.build.json b/tsconfig.build.json
index ed15c9f6d0..ff34d49c0a 100644
--- a/tsconfig.build.json
+++ b/tsconfig.build.json
@@ -3,9 +3,10 @@
   "extends": "./tsconfig.base.json",
   "include": ["src"],
   "exclude": [
+    "src/**/*.bench.ts",
+    "src/**/*.bench-d.ts",
     "src/**/*.test.ts",
     "src/**/*.test-d.ts",
-    "src/**/*.bench.ts",
     "src/node/trustedSetups_esm.ts"
   ],
   "compilerOptions": {
diff --git a/vercel.json b/vercel.json
deleted file mode 100644
index 3c092d8c9a..0000000000
--- a/vercel.json
+++ /dev/null
@@ -1,8 +0,0 @@
-{
-  "rewrites": [
-    {
-      "source": "/:match*.html",
-      "destination": "/:match"
-    }
-  ]
-}