diff --git a/package.json b/package.json
index c319f0b3..bc66fbd4 100644
--- a/package.json
+++ b/package.json
@@ -53,6 +53,7 @@
     "lint-fix": "eslint --fix src/ addons/ demo/",
     "lint-api": "eslint --config eslint.config.typings.mjs --max-warnings 0 typings/",
     "test-unit": "node ./bin/test_unit.js",
+    "test-unit-slow-tests": "npm run test-unit | grep \"ms)\"",
     "test-unit-coverage": "node ./bin/test_unit.js --coverage",
     "test-unit-dev": "cross-env NODE_PATH='./out' mocha",
     "test-integration": "node ./bin/test_integration.js --workers=75%",
diff --git a/src/common/parser/ApcParser.test.ts b/src/common/parser/ApcParser.test.ts
index 3401baab..f337e5c0 100644
--- a/src/common/parser/ApcParser.test.ts
+++ b/src/common/parser/ApcParser.test.ts
@@ -6,7 +6,6 @@ import { assert } from 'chai';
 import { ApcParser, ApcHandler } from 'common/parser/ApcParser';
 import { StringToUtf32, utf32ToString } from 'common/input/TextDecoder';
 import { IApcHandler } from 'common/parser/Types';
-import { PAYLOAD_LIMIT } from 'common/parser/Constants';
 
 function toUtf32(s: string): Uint32Array {
   const utf32 = new Uint32Array(s.length);
@@ -216,6 +215,21 @@ describe('ApcParser', () => {
   });
 
   describe('ApcHandler convenience class', () => {
+    const TEST_PAYLOAD_LIMIT = 100;
+    const CHUNK_SIZE = 10;
+    let originalPayloadLimit: number;
+
+    beforeEach(() => {
+      const handlerConstructor = ApcHandler as unknown as { PAYLOAD_LIMIT: number };
+      originalPayloadLimit = handlerConstructor.PAYLOAD_LIMIT;
+      handlerConstructor.PAYLOAD_LIMIT = TEST_PAYLOAD_LIMIT;
+    });
+
+    afterEach(() => {
+      const handlerConstructor = ApcHandler as unknown as { PAYLOAD_LIMIT: number };
+      handlerConstructor.PAYLOAD_LIMIT = originalPayloadLimit;
+    });
+
     it('should be called once on end(true)', () => {
       const G_CODE = 0x47;
       const results: [number, string][] = [];
@@ -257,12 +271,12 @@ describe('ApcParser', () => {
       parser.start();
       let data = toUtf32('G');
       parser.put(data, 0, data.length);
-      data = toUtf32('A'.repeat(1000));
-      for (let i = 0; i < PAYLOAD_LIMIT; i += 1000) {
+      data = toUtf32('A'.repeat(CHUNK_SIZE));
+      for (let i = 0; i < TEST_PAYLOAD_LIMIT; i += CHUNK_SIZE) {
         parser.put(data, 0, data.length);
       }
       parser.end(true);
-      assert.deepEqual(results, [[G_CODE, 'A'.repeat(PAYLOAD_LIMIT)]]);
+      assert.deepEqual(results, [[G_CODE, 'A'.repeat(TEST_PAYLOAD_LIMIT)]]);
     });
 
     it('should abort for payload over limit', function(): void {
@@ -276,8 +290,8 @@ describe('ApcParser', () => {
       parser.start();
       let data = toUtf32('G');
       parser.put(data, 0, data.length);
-      data = toUtf32('A'.repeat(1000));
-      for (let i = 0; i < PAYLOAD_LIMIT; i += 1000) {
+      data = toUtf32('A'.repeat(CHUNK_SIZE));
+      for (let i = 0; i < TEST_PAYLOAD_LIMIT; i += CHUNK_SIZE) {
         parser.put(data, 0, data.length);
       }
       data = toUtf32('A');
diff --git a/src/common/parser/DcsParser.test.ts b/src/common/parser/DcsParser.test.ts
index c6cc0994..0c09199a 100644
--- a/src/common/parser/DcsParser.test.ts
+++ b/src/common/parser/DcsParser.test.ts
@@ -7,7 +7,6 @@ import { DcsParser, DcsHandler } from 'common/parser/DcsParser';
 import { IDcsHandler, IParams, IFunctionIdentifier } from 'common/parser/Types';
 import { utf32ToString, StringToUtf32 } from 'common/input/TextDecoder';
 import { Params } from 'common/parser/Params';
-import { PAYLOAD_LIMIT } from 'common/parser/Constants';
 
 function toUtf32(s: string): Uint32Array {
   const utf32 = new Uint32Array(s.length);
@@ -176,6 +175,21 @@ describe('DcsParser', () => {
     });
   });
   describe('DcsHandlerFactory', () => {
+    const TEST_PAYLOAD_LIMIT = 100;
+    const CHUNK_SIZE = 10;
+    let originalPayloadLimit: number;
+
+    beforeEach(() => {
+      const handlerConstructor = DcsHandler as unknown as { PAYLOAD_LIMIT: number };
+      originalPayloadLimit = handlerConstructor.PAYLOAD_LIMIT;
+      handlerConstructor.PAYLOAD_LIMIT = TEST_PAYLOAD_LIMIT;
+    });
+
+    afterEach(() => {
+      const handlerConstructor = DcsHandler as unknown as { PAYLOAD_LIMIT: number };
+      handlerConstructor.PAYLOAD_LIMIT = originalPayloadLimit;
+    });
+
     it('should be called once on end(true)', () => {
       parser.registerHandler(identifier({intermediates: '+', final: 'p'}), new DcsHandler((data, params) => { reports.push([params.toArray(), data]); return true; }));
       parser.hook(identifier({intermediates: '+', final: 'p'}), Params.fromArray([1, 2, 3]));
@@ -230,19 +244,19 @@ describe('DcsParser', () => {
       this.timeout(30000);
       parser.registerHandler(identifier({intermediates: '+', final: 'p'}), new DcsHandler((data, params) => { reports.push([params.toArray(), data]); return true; }));
       parser.hook(identifier({intermediates: '+', final: 'p'}), Params.fromArray([1, 2, 3]));
-      const data = toUtf32('A'.repeat(1000));
-      for (let i = 0; i < PAYLOAD_LIMIT; i += 1000) {
+      const data = toUtf32('A'.repeat(CHUNK_SIZE));
+      for (let i = 0; i < TEST_PAYLOAD_LIMIT; i += CHUNK_SIZE) {
         parser.put(data, 0, data.length);
       }
       parser.unhook(true);
-      assert.deepEqual(reports, [[[1, 2, 3], 'A'.repeat(PAYLOAD_LIMIT)]]);
+      assert.deepEqual(reports, [[[1, 2, 3], 'A'.repeat(TEST_PAYLOAD_LIMIT)]]);
     });
     it('should abort for payload limit +1', function(): void {
       this.timeout(30000);
       parser.registerHandler(identifier({intermediates: '+', final: 'p'}), new DcsHandler((data, params) => { reports.push([params.toArray(), data]); return true; }));
       parser.hook(identifier({intermediates: '+', final: 'p'}), Params.fromArray([1, 2, 3]));
-      let data = toUtf32('A'.repeat(1000));
-      for (let i = 0; i < PAYLOAD_LIMIT; i += 1000) {
+      let data = toUtf32('A'.repeat(CHUNK_SIZE));
+      for (let i = 0; i < TEST_PAYLOAD_LIMIT; i += CHUNK_SIZE) {
         parser.put(data, 0, data.length);
       }
       data = toUtf32('A');
diff --git a/src/common/parser/OscParser.test.ts b/src/common/parser/OscParser.test.ts
index b88171c8..cad73352 100644
--- a/src/common/parser/OscParser.test.ts
+++ b/src/common/parser/OscParser.test.ts
@@ -6,7 +6,6 @@ import { assert } from 'chai';
 import { OscParser, OscHandler } from 'common/parser/OscParser';
 import { StringToUtf32, utf32ToString } from 'common/input/TextDecoder';
 import { IOscHandler } from 'common/parser/Types';
-import { PAYLOAD_LIMIT } from 'common/parser/Constants';
 
 function toUtf32(s: string): Uint32Array {
   const utf32 = new Uint32Array(s.length);
@@ -170,6 +169,21 @@ describe('OscParser', () => {
     });
   });
   describe('OscHandlerFactory', () => {
+    const TEST_PAYLOAD_LIMIT = 100;
+    const CHUNK_SIZE = 10;
+    let originalPayloadLimit: number;
+
+    beforeEach(() => {
+      const handlerConstructor = OscHandler as unknown as { PAYLOAD_LIMIT: number };
+      originalPayloadLimit = handlerConstructor.PAYLOAD_LIMIT;
+      handlerConstructor.PAYLOAD_LIMIT = TEST_PAYLOAD_LIMIT;
+    });
+
+    afterEach(() => {
+      const handlerConstructor = OscHandler as unknown as { PAYLOAD_LIMIT: number };
+      handlerConstructor.PAYLOAD_LIMIT = originalPayloadLimit;
+    });
+
     it('should be called once on end(true)', () => {
       parser.registerHandler(1234, new OscHandler(data => { reports.push([1234, data]); return true; }));
       parser.start();
@@ -226,12 +240,12 @@ describe('OscParser', () => {
       parser.start();
       let data = toUtf32('1234;');
       parser.put(data, 0, data.length);
-      data = toUtf32('A'.repeat(1000));
-      for (let i = 0; i < PAYLOAD_LIMIT; i += 1000) {
+      data = toUtf32('A'.repeat(CHUNK_SIZE));
+      for (let i = 0; i < TEST_PAYLOAD_LIMIT; i += CHUNK_SIZE) {
         parser.put(data, 0, data.length);
       }
       parser.end(true);
-      assert.deepEqual(reports, [[1234, 'A'.repeat(PAYLOAD_LIMIT)]]);
+      assert.deepEqual(reports, [[1234, 'A'.repeat(TEST_PAYLOAD_LIMIT)]]);
     });
     it('should abort for payload limit +1', function(): void {
       this.timeout(30000);
@@ -239,8 +253,8 @@ describe('OscParser', () => {
       parser.start();
       let data = toUtf32('1234;');
       parser.put(data, 0, data.length);
-      data = toUtf32('A'.repeat(1000));
-      for (let i = 0; i < PAYLOAD_LIMIT; i += 1000) {
+      data = toUtf32('A'.repeat(CHUNK_SIZE));
+      for (let i = 0; i < TEST_PAYLOAD_LIMIT; i += CHUNK_SIZE) {
         parser.put(data, 0, data.length);
       }
       data = toUtf32('A');