@@ -32,6 +32,8 @@ Returns: `Client`
 * **allowH2**: `boolean` - Default: `false`. Enables support for H2 if the server has assigned bigger priority to it through ALPN negotiation.
 * **useH2c**: `boolean` - Default: `false`. Enforces h2c for non-https connections.
 * **maxConcurrentStreams**: `number` - Default: `100`. Dictates the maximum number of concurrent streams for a single H2 session. It can be overridden by a SETTINGS remote frame.
+* **initialWindowSize**: `number` (optional) - Default: `262144` (256KB). Sets the HTTP/2 stream-level flow-control window size (SETTINGS_INITIAL_WINDOW_SIZE). Must be a positive integer greater than 0. This default is higher than Node.js core's default (65535 bytes) to improve throughput, Node's choice is very conservative for current high-bandwith networks. See [RFC 7540 Section 6.9.2](https://datatracker.ietf.org/doc/html/rfc7540#section-6.9.2) for more details.
+* **connectionWindowSize**: `number` (optional) - Default `524288` (512KB). Sets the HTTP/2 connection-level flow-control window size using `ClientHttp2Session.setLocalWindowSize()`. Must be a positive integer greater than 0. This provides better flow control for the entire connection across multiple streams. See [Node.js HTTP/2 documentation](https://nodejs.org/api/http2.html#clienthttp2sessionsetlocalwindowsize) for more details.
 
 > **Notes about HTTP/2**
 > - It only works under TLS connections. h2c is not supported.
 
@@ -62,6 +62,8 @@ module.exports = {
   kListeners: Symbol('listeners'),
   kHTTPContext: Symbol('http context'),
   kMaxConcurrentStreams: Symbol('max concurrent streams'),
+  kHTTP2InitialWindowSize: Symbol('http2 initial window size'),
+  kHTTP2ConnectionWindowSize: Symbol('http2 connection window size'),
   kEnableConnectProtocol: Symbol('http2session connect protocol'),
   kRemoteSettings: Symbol('http2session remote settings'),
   kHTTP2Stream: Symbol('http2session client stream'),
 
@@ -58,6 +58,8 @@ function wrapRequestBody (body) {
     // to determine whether or not it has been disturbed. This is just
     // a workaround.
     return new BodyAsyncIterable(body)
+  } else if (body && isFormDataLike(body)) {
+    return body
   } else if (
     body &&
     typeof body !== 'string' &&
 
@@ -25,6 +25,8 @@ const {
   kOnError,
   kMaxConcurrentStreams,
   kHTTP2Session,
+  kHTTP2InitialWindowSize,
+  kHTTP2ConnectionWindowSize,
   kResume,
   kSize,
   kHTTPContext,
@@ -87,12 +89,16 @@ function parseH2Headers (headers) {
 function connectH2 (client, socket) {
   client[kSocket] = socket
 
+  const http2InitialWindowSize = client[kHTTP2InitialWindowSize]
+  const http2ConnectionWindowSize = client[kHTTP2ConnectionWindowSize]
+
   const session = http2.connect(client[kUrl], {
     createConnection: () => socket,
     peerMaxConcurrentStreams: client[kMaxConcurrentStreams],
     settings: {
       // TODO(metcoder95): add support for PUSH
-      enablePush: false
+      enablePush: false,
+      ...(http2InitialWindowSize != null ? { initialWindowSize: http2InitialWindowSize } : null)
     }
   })
 
@@ -107,6 +113,11 @@ function connectH2 (client, socket) {
   // States whether or not we have received the remote settings from the server
   session[kRemoteSettings] = false
 
+  // Apply connection-level flow control once connected (if supported).
+  if (http2ConnectionWindowSize) {
+    util.addListener(session, 'connect', applyConnectionWindowSize.bind(session, http2ConnectionWindowSize))
+  }
+
   util.addListener(session, 'error', onHttp2SessionError)
   util.addListener(session, 'frameError', onHttp2FrameError)
   util.addListener(session, 'end', onHttp2SessionEnd)
@@ -211,6 +222,16 @@ function resumeH2 (client) {
   }
 }
 
+function applyConnectionWindowSize (connectionWindowSize) {
+  try {
+    if (typeof this.setLocalWindowSize === 'function') {
+      this.setLocalWindowSize(connectionWindowSize)
+    }
+  } catch {
+    // Best-effort only.
+  }
+}
+
 function onHttp2RemoteSettings (settings) {
   // Fallbacks are a safe bet, remote setting will always override
   this[kClient][kMaxConcurrentStreams] = settings.maxConcurrentStreams ?? this[kClient][kMaxConcurrentStreams]
 
@@ -52,6 +52,8 @@ const {
   kOnError,
   kHTTPContext,
   kMaxConcurrentStreams,
+  kHTTP2InitialWindowSize,
+  kHTTP2ConnectionWindowSize,
   kResume
 } = require('../core/symbols.js')
 const connectH1 = require('./client-h1.js')
@@ -108,7 +110,9 @@ class Client extends DispatcherBase {
     // h2
     maxConcurrentStreams,
     allowH2,
-    useH2c
+    useH2c,
+    initialWindowSize,
+    connectionWindowSize
   } = {}) {
     if (keepAlive !== undefined) {
       throw new InvalidArgumentError('unsupported keepAlive, use pipelining=0 instead')
@@ -204,6 +208,14 @@ class Client extends DispatcherBase {
       throw new InvalidArgumentError('useH2c must be a valid boolean value')
     }
 
+    if (initialWindowSize != null && (!Number.isInteger(initialWindowSize) || initialWindowSize < 1)) {
+      throw new InvalidArgumentError('initialWindowSize must be a positive integer, greater than 0')
+    }
+
+    if (connectionWindowSize != null && (!Number.isInteger(connectionWindowSize) || connectionWindowSize < 1)) {
+      throw new InvalidArgumentError('connectionWindowSize must be a positive integer, greater than 0')
+    }
+
     super()
 
     if (typeof connect !== 'function') {
@@ -239,6 +251,14 @@ class Client extends DispatcherBase {
     this[kClosedResolve] = null
     this[kMaxResponseSize] = maxResponseSize > -1 ? maxResponseSize : -1
     this[kMaxConcurrentStreams] = maxConcurrentStreams != null ? maxConcurrentStreams : 100 // Max peerConcurrentStreams for a Node h2 server
+    // HTTP/2 window sizes are set to higher defaults than Node.js core for better performance:
+    // - initialWindowSize: 262144 (256KB) vs Node.js default 65535 (64KB - 1)
+    //   Allows more data to be sent before requiring acknowledgment, improving throughput
+    //   especially on high-latency networks. This matches common production HTTP/2 servers.
+    // - connectionWindowSize: 524288 (512KB) vs Node.js default (none set)
+    //   Provides better flow control for the entire connection across multiple streams.
+    this[kHTTP2InitialWindowSize] = initialWindowSize != null ? initialWindowSize : 262144
+    this[kHTTP2ConnectionWindowSize] = connectionWindowSize != null ? connectionWindowSize : 524288
     this[kHTTPContext] = null
 
     // kQueue is built up of 3 sections separated by
 
@@ -9,6 +9,23 @@ const CacheRevalidationHandler = require('../handler/cache-revalidation-handler'
 const { assertCacheStore, assertCacheMethods, makeCacheKey, normalizeHeaders, parseCacheControlHeader } = require('../util/cache.js')
 const { AbortError } = require('../core/errors.js')
 
+/**
+ * @param {(string | RegExp)[] | undefined} origins
+ * @param {string} name
+ */
+function assertCacheOrigins (origins, name) {
+  if (origins === undefined) return
+  if (!Array.isArray(origins)) {
+    throw new TypeError(`expected ${name} to be an array or undefined, got ${typeof origins}`)
+  }
+  for (let i = 0; i < origins.length; i++) {
+    const origin = origins[i]
+    if (typeof origin !== 'string' && !(origin instanceof RegExp)) {
+      throw new TypeError(`expected ${name}[${i}] to be a string or RegExp, got ${typeof origin}`)
+    }
+  }
+}
+
 const nop = () => {}
 
 /**
@@ -372,7 +389,8 @@ module.exports = (opts = {}) => {
     store = new MemoryCacheStore(),
     methods = ['GET'],
     cacheByDefault = undefined,
-    type = 'shared'
+    type = 'shared',
+    origins = undefined
   } = opts
 
   if (typeof opts !== 'object' || opts === null) {
@@ -381,6 +399,7 @@ module.exports = (opts = {}) => {
 
   assertCacheStore(store, 'opts.store')
   assertCacheMethods(methods, 'opts.methods')
+  assertCacheOrigins(origins, 'opts.origins')
 
   if (typeof cacheByDefault !== 'undefined' && typeof cacheByDefault !== 'number') {
     throw new TypeError(`expected opts.cacheByDefault to be number or undefined, got ${typeof cacheByDefault}`)
@@ -406,6 +425,29 @@ module.exports = (opts = {}) => {
         return dispatch(opts, handler)
       }
 
+      // Check if origin is in whitelist
+      if (origins !== undefined) {
+        const requestOrigin = opts.origin.toString().toLowerCase()
+        let isAllowed = false
+
+        for (let i = 0; i < origins.length; i++) {
+          const allowed = origins[i]
+          if (typeof allowed === 'string') {
+            if (allowed.toLowerCase() === requestOrigin) {
+              isAllowed = true
+              break
+            }
+          } else if (allowed.test(requestOrigin)) {
+            isAllowed = true
+            break
+          }
+        }
+
+        if (!isAllowed) {
+          return dispatch(opts, handler)
+        }
+      }
+
       opts = {
         ...opts,
         headers: normalizeHeaders(opts)
 
@@ -1,5 +1,5 @@
 
-> undici@7.18.2 build:wasm
+> undici@7.19.0 build:wasm
 > node build/wasm.js --docker
 
 > docker run --rm --platform=linux/x86_64  --user 1001:1001 --mount type=bind,source=/home/runner/work/node/node/deps/undici/src/lib/llhttp,target=/home/node/build/lib/llhttp            --mount type=bind,source=/home/runner/work/node/node/deps/undici/src/build,target=/home/node/build/build            --mount type=bind,source=/home/runner/work/node/node/deps/undici/src/deps,target=/home/node/build/deps            -t ghcr.io/nodejs/wasm-builder@sha256:975f391d907e42a75b8c72eb77c782181e941608687d4d8694c3e9df415a0970 node build/wasm.js
 
@@ -22,7 +22,7 @@ const {
 } = require('./mock-symbols')
 const MockClient = require('./mock-client')
 const MockPool = require('./mock-pool')
-const { matchValue, normalizeSearchParams, buildAndValidateMockOptions } = require('./mock-utils')
+const { matchValue, normalizeSearchParams, buildAndValidateMockOptions, normalizeOrigin } = require('./mock-utils')
 const { InvalidArgumentError, UndiciError } = require('../core/errors')
 const Dispatcher = require('../dispatcher/dispatcher')
 const PendingInterceptorsFormatter = require('./pending-interceptors-formatter')
@@ -56,9 +56,9 @@ class MockAgent extends Dispatcher {
   }
 
   get (origin) {
-    const originKey = this[kIgnoreTrailingSlash]
-      ? origin.replace(/\/$/, '')
-      : origin
+    // Normalize origin to handle URL objects and case-insensitive hostnames
+    const normalizedOrigin = normalizeOrigin(origin)
+    const originKey = this[kIgnoreTrailingSlash] ? normalizedOrigin.replace(/\/$/, '') : normalizedOrigin
 
     let dispatcher = this[kMockAgentGet](originKey)
 
@@ -70,6 +70,8 @@ class MockAgent extends Dispatcher {
   }
 
   dispatch (opts, handler) {
+    opts.origin = normalizeOrigin(opts.origin)
+
     // Call MockAgent.get to perform additional setup before dispatching as normal
     this.get(opts.origin)
 
 
@@ -396,6 +396,18 @@ function checkNetConnect (netConnect, origin) {
   return false
 }
 
+function normalizeOrigin (origin) {
+  if (typeof origin !== 'string' && !(origin instanceof URL)) {
+    return origin
+  }
+
+  if (origin instanceof URL) {
+    return origin.origin
+  }
+
+  return origin.toLowerCase()
+}
+
 function buildAndValidateMockOptions (opts) {
   const { agent, ...mockOptions } = opts
 
@@ -430,5 +442,6 @@ module.exports = {
   buildAndValidateMockOptions,
   getHeaderByName,
   buildHeadersFromArray,
-  normalizeSearchParams
+  normalizeSearchParams,
+  normalizeOrigin
 }
@@ -794,9 +794,9 @@ class Cache {
     // 5.5.2
     for (const response of responses) {
       // 5.5.2.1
-      const responseObject = fromInnerResponse(response, 'immutable')
+      const responseObject = fromInnerResponse(cloneResponse(response), 'immutable')
 
-      responseList.push(responseObject.clone())
+      responseList.push(responseObject)
 
       if (responseList.length >= maxResponses) {
         break