diff --git a/.circleci/config.yml b/.circleci/config.yml
index d690389..295d01c 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -7,7 +7,7 @@ jobs:
   build:
     docker:
       # specify the version you desire here
-      - image: circleci/node:8.11
+      - image: circleci/node:10.0.0
 
     working_directory: ~/repo
 
diff --git a/README.md b/README.md
index ae7190f..a9ee162 100644
--- a/README.md
+++ b/README.md
@@ -53,6 +53,31 @@ async function logMessagesFromFooBar() {
 logMessagesFromFooBar();
 ```
 
+If you're dealing with large rosbag files and need flow control to process messages async, use the Async Generator `iterateMessages`.
+
+```js
+const { open } = require('rosbag');
+
+async function readWithAsyncConsumer () {
+  const options = { topics: ['/unicorns'] };
+  const bag = await open("filename.bag");
+  for await (const msg of bag.iterateMessages(options)) {
+    // each message is read separately
+    // respecting async behavior in the for loop
+    await doSomethingAsync(msg);
+  }
+}
+
+readWithAsyncConsumer()
+  .then(() => console.log("DONE"));
+
+```
+
+That way you can also create a readable message stream
+```js
+  require("stream").Readable.from(bag.iterateMessages(options))
+```
+
 ## API
 
 ### Opening a new rosbag reader
diff --git a/package.json b/package.json
index 1d45e96..cbbccda 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "rosbag",
-  "version": "2.6.1",
+  "version": "2.6.3",
   "license": "Apache-2.0",
   "repository": "cruise-automation/rosbag.js",
   "dependencies": {
@@ -9,7 +9,7 @@
     "int53": "1.0.0"
   },
   "engines": {
-    "node": ">=8.0.0"
+    "node": ">=10.0.0"
   },
   "main": "dist/node",
   "browser": "dist/web",
diff --git a/src/bag.js b/src/bag.js
index 383a86a..c37c157 100644
--- a/src/bag.js
+++ b/src/bag.js
@@ -74,6 +74,12 @@ export default class Bag {
   }
 
   async readMessages(opts: ReadOptions, callback: (msg: ReadResult<any>) => void) {
+    for await (const msg of this.iterateMessages(opts)) {
+      callback(msg);
+    }
+  }
+
+  async *iterateMessages(opts: ReadOptions): AsyncGenerator<ReadResult<any>, void, number> {
     const connections = this.connections;
 
     const startTime = opts.startTime || { sec: 0, nsec: 0 };
@@ -121,7 +127,9 @@ export default class Bag {
         endTime,
         decompress
       );
-      messages.forEach((msg) => callback(parseMsg(msg, i)));
+      for (const msg of messages) {
+        if (yield parseMsg(msg, i)) return;
+      }
     }
   }
 }
diff --git a/src/bag.test.js b/src/bag.test.js
index b3be8ac..0bd26e6 100644
--- a/src/bag.test.js
+++ b/src/bag.test.js
@@ -211,6 +211,23 @@ describe("rosbag - high-level api", () => {
     expect(messages).toHaveLength(9);
   });
 
+  it("reads at consumer speed and abort reading on demand", async () => {
+    const delay = (ms) => new Promise((resolve) => setTimeout(resolve, ms));
+    const opts = { topics: ["/tf"] };
+    const bag = await Bag.open(getFixture());
+    const messages = bag.iterateMessages(opts || {});
+    const r1 = await messages.next();
+    expect(r1.value.timestamp.nsec).toBe(56251251);
+    expect(r1.done).toBe(false);
+    await delay(100);
+    const r2 = await messages.next();
+    expect(r2.value.timestamp.nsec).toBe(56262848);
+    expect(r2.done).toBe(false);
+    await delay(100);
+    const r3 = await messages.next(true);
+    expect(r3.done).toBe(true);
+  });
+
   describe("compression", () => {
     it("throws if compression scheme is not registered", async () => {
       let errorThrown = false;
diff --git a/src/fields.js b/src/fields.js
index ca5d6c1..ab1fc13 100644
--- a/src/fields.js
+++ b/src/fields.js
@@ -11,6 +11,7 @@ import type { Time } from "./types";
 // reads through a buffer and extracts { [key: string]: value: string }
 // pairs - the buffer is expected to have length prefixed utf8 strings
 // with a '=' separating the key and value
+const EQUALS_CHARCODE = "=".charCodeAt(0);
 export function extractFields(buffer: Buffer) {
   if (buffer.length < 4) {
     throw new Error("Header fields are truncated.");
@@ -27,8 +28,10 @@ export function extractFields(buffer: Buffer) {
       throw new Error("Header fields are corrupt.");
     }
 
+    // Passing a number into "indexOf" explicitly to avoid Buffer polyfill
+    // slow path. See issue #87.
     const field = buffer.slice(i, i + length);
-    const index = field.indexOf("=");
+    const index = field.indexOf(EQUALS_CHARCODE);
     if (index === -1) {
       throw new Error("Header field is missing equals sign.");
     }
diff --git a/src/types.js b/src/types.js
index a658407..3a37215 100644
--- a/src/types.js
+++ b/src/types.js
@@ -23,25 +23,19 @@ export interface Filelike {
   size(): number;
 }
 
-export type RosMsgField =
-  | {|
-      type: string,
-      name: string,
-      isConstant?: boolean,
-      isComplex?: boolean,
-      value?: mixed,
-      isArray?: false,
-      arrayLength?: void,
-    |}
-  | {|
-      type: string,
-      name: string,
-      isConstant?: boolean,
-      isComplex?: boolean,
-      value?: mixed,
-      isArray: true,
-      arrayLength: ?number,
-    |};
+export type RosMsgField = {|
+  type: string,
+  name: string,
+  isComplex?: boolean,
+
+  // For arrays
+  isArray?: boolean,
+  arrayLength?: ?number,
+
+  // For constants
+  isConstant?: boolean,
+  value?: mixed,
+|};
 
 export type RosMsgDefinition = {|
   name?: string,