diff --git a/packages/babel-cli/src/babel-external-helpers.ts b/packages/babel-cli/src/babel-external-helpers.ts
index 5c6ef24de6ca..ca09b8ae0bc7 100755
--- a/packages/babel-cli/src/babel-external-helpers.ts
+++ b/packages/babel-cli/src/babel-external-helpers.ts
@@ -10,7 +10,11 @@ function collect(
 
   const values = value.split(",");
 
-  return previousValue ? previousValue.concat(values) : values;
+  if (previousValue) {
+    Array.prototype.push.apply(previousValue, values);
+    return previousValue;
+  }
+  return values;
 }
 
 commander.option(
diff --git a/packages/babel-cli/src/babel/options.ts b/packages/babel-cli/src/babel/options.ts
index 19eb9b20c62c..98f67bb0b6d3 100644
--- a/packages/babel-cli/src/babel/options.ts
+++ b/packages/babel-cli/src/babel/options.ts
@@ -192,7 +192,8 @@ export default function parseArgv(args: Array<string>): CmdOptions | null {
   let filenames = commander.args.reduce(function (globbed, input) {
     let files = glob.sync(input);
     if (!files.length) files = [input];
-    return globbed.concat(files);
+    Array.prototype.push.apply(globbed, files);
+    return globbed;
   }, []);
 
   filenames = Array.from(new Set(filenames));
@@ -353,5 +354,9 @@ function collect(
 
   const values = value.split(",");
 
-  return previousValue ? previousValue.concat(values) : values;
+  if (previousValue) {
+    Array.prototype.push.apply(previousValue, values);
+    return previousValue;
+  }
+  return values;
 }
diff --git a/packages/babel-helper-define-map/src/index.js b/packages/babel-helper-define-map/src/index.js
index 290a50c20202..463026389064 100644
--- a/packages/babel-helper-define-map/src/index.js
+++ b/packages/babel-helper-define-map/src/index.js
@@ -42,7 +42,8 @@ export function push(
   if (node.decorators) {
     const decorators = (map.decorators =
       map.decorators || t.arrayExpression([]));
-    decorators.elements = decorators.elements.concat(
+    Array.prototype.push.apply(
+      decorators.elements,
       node.decorators.map(dec => dec.expression).reverse(),
     );
   }
diff --git a/packages/babel-helpers/src/helpers.js b/packages/babel-helpers/src/helpers.js
index 4397c0f817bb..73ac517b1fd8 100644
--- a/packages/babel-helpers/src/helpers.js
+++ b/packages/babel-helpers/src/helpers.js
@@ -316,7 +316,7 @@ helpers.extends = helper("7.0.0-beta.0")`
   }
 `;
 
-// This old helper can be removed in babel v8
+// TODO(babel-8): This old helper can be removed in babel v8
 helpers.objectSpread = helper("7.0.0-beta.0")`
   import defineProperty from "defineProperty";
 
@@ -325,7 +325,7 @@ helpers.objectSpread = helper("7.0.0-beta.0")`
       var source = (arguments[i] != null) ? Object(arguments[i]) : {};
       var ownKeys = Object.keys(source);
       if (typeof Object.getOwnPropertySymbols === 'function') {
-        ownKeys = ownKeys.concat(Object.getOwnPropertySymbols(source).filter(function(sym) {
+        Array.prototype.push.apply(ownKeys, Object.getOwnPropertySymbols(source).filter(function(sym) {
           return Object.getOwnPropertyDescriptor(source, sym).enumerable;
         }));
       }
diff --git a/packages/babel-node/src/_babel-node.js b/packages/babel-node/src/_babel-node.js
index 9792d975831a..52f03b40a932 100644
--- a/packages/babel-node/src/_babel-node.js
+++ b/packages/babel-node/src/_babel-node.js
@@ -21,7 +21,11 @@ function collect(value, previousValue): Array<string> {
 
   const values = value.split(",");
 
-  return previousValue ? previousValue.concat(values) : values;
+  if (previousValue) {
+    Array.prototype.push.apply(previousValue, values);
+    return previousValue;
+  }
+  return values;
 }
 
 program.option("-e, --eval [script]", "Evaluate script");
@@ -197,7 +201,7 @@ if (program.eval || program.print) {
     }
 
     // add back on node and concat the sliced args
-    process.argv = ["node"].concat(args);
+    process.argv = ["node", ...args];
     process.execArgv.push(fileURLToPath(import.meta.url));
 
     Module.runMain();
diff --git a/packages/babel-node/src/babel-node.js b/packages/babel-node/src/babel-node.js
index 8ef4607f58f2..5fd1885c1b37 100755
--- a/packages/babel-node/src/babel-node.js
+++ b/packages/babel-node/src/babel-node.js
@@ -8,7 +8,7 @@ import path from "path";
 import child_process from "child_process";
 import { fileURLToPath } from "url";
 
-let args = [
+const args = [
   path.join(path.dirname(fileURLToPath(import.meta.url)), "_babel-node"),
 ];
 
@@ -69,7 +69,7 @@ getV8Flags(async function (err, v8Flags) {
 
   // append arguments passed after --
   if (argSeparator > -1) {
-    args = args.concat(userArgs);
+    Array.prototype.push.apply(args, userArgs);
   }
 
   try {
diff --git a/packages/babel-parser/src/plugins/flow/index.js b/packages/babel-parser/src/plugins/flow/index.js
index dbb95972673a..24ecc33e5d66 100644
--- a/packages/babel-parser/src/plugins/flow/index.js
+++ b/packages/babel-parser/src/plugins/flow/index.js
@@ -1963,7 +1963,8 @@ export default (superClass: Class<Parser>): Class<Parser> =>
 
         if (failed && valid.length === 1) {
           this.state = state;
-          this.state.noArrowAt = noArrowAt.concat(valid[0].start);
+          noArrowAt.push(valid[0].start);
+          this.state.noArrowAt = noArrowAt;
           ({ consequent, failed } = this.tryParseConditionalConsequent());
         }
       }
diff --git a/packages/babel-plugin-proposal-async-generator-functions/src/index.js b/packages/babel-plugin-proposal-async-generator-functions/src/index.js
index a81607084357..4711f9e2b3fa 100644
--- a/packages/babel-plugin-proposal-async-generator-functions/src/index.js
+++ b/packages/babel-plugin-proposal-async-generator-functions/src/index.js
@@ -47,7 +47,7 @@ export default declare(api => {
       }
 
       // push the rest of the original loop body onto our new body
-      block.body = block.body.concat(node.body.body);
+      Array.prototype.push.apply(block.body, node.body.body);
 
       t.inherits(loop, node);
       t.inherits(loop.body, node.body);
diff --git a/packages/babel-plugin-proposal-decorators/src/transformer-legacy.js b/packages/babel-plugin-proposal-decorators/src/transformer-legacy.js
index e19a775524cf..5b8dd8d202b8 100644
--- a/packages/babel-plugin-proposal-decorators/src/transformer-legacy.js
+++ b/packages/babel-plugin-proposal-decorators/src/transformer-legacy.js
@@ -157,7 +157,7 @@ function applyTargetDecorators(path, state, decoratedProps) {
 
       WARNING_CALLS.add(node.value);
 
-      acc = acc.concat([
+      acc.push(
         t.assignmentExpression(
           "=",
           t.cloneNode(descriptor),
@@ -184,9 +184,9 @@ function applyTargetDecorators(path, state, decoratedProps) {
             ]),
           ]),
         ),
-      ]);
+      );
     } else {
-      acc = acc.concat(
+      acc.push(
         t.callExpression(state.addHelper("applyDecoratedDescriptor"), [
           t.cloneNode(target),
           t.cloneNode(property),
diff --git a/packages/babel-plugin-transform-classes/src/transformClass.ts b/packages/babel-plugin-transform-classes/src/transformClass.ts
index 4f4a8b6b332e..a7bd7593f952 100644
--- a/packages/babel-plugin-transform-classes/src/transformClass.ts
+++ b/packages/babel-plugin-transform-classes/src/transformClass.ts
@@ -136,7 +136,8 @@ export default function transformClass(
 
     if (classState.userConstructor) {
       const { constructorBody, userConstructor, construct } = classState;
-      constructorBody.body = constructorBody.body.concat(
+      Array.prototype.push.apply(
+        constructorBody.body,
         userConstructor.body.body,
       );
       t.inherits(construct, userConstructor);
@@ -695,7 +696,7 @@ export default function transformClass(
 
     extractDynamicKeys();
 
-    let { body } = classState;
+    const { body } = classState;
     const { closureParams, closureArgs } = setupClosureParamsArgs();
 
     buildBody();
@@ -712,7 +713,8 @@ export default function transformClass(
       );
     }
 
-    body = body.concat(
+    Array.prototype.push.apply(
+      body,
       classState.staticPropBody.map(fn => fn(t.cloneNode(classState.classRef))),
     );
 
diff --git a/packages/babel-plugin-transform-for-of/src/no-helper-implementation.js b/packages/babel-plugin-transform-for-of/src/no-helper-implementation.js
index 2624f0bc9093..837aef94841d 100644
--- a/packages/babel-plugin-transform-for-of/src/no-helper-implementation.js
+++ b/packages/babel-plugin-transform-for-of/src/no-helper-implementation.js
@@ -24,7 +24,7 @@ export default function transformWithoutHelper(loose, path, state) {
   }
 
   // push the rest of the original loop body onto our new body
-  block.body = block.body.concat(node.body.body);
+  Array.prototype.push.apply(block.body, node.body.body);
 
   t.inherits(loop, node);
   t.inherits(loop.body, node.body);
diff --git a/packages/babel-plugin-transform-modules-systemjs/src/index.js b/packages/babel-plugin-transform-modules-systemjs/src/index.js
index 4dd75d8146cc..e7fa09c9f6e3 100644
--- a/packages/babel-plugin-transform-modules-systemjs/src/index.js
+++ b/packages/babel-plugin-transform-modules-systemjs/src/index.js
@@ -295,7 +295,7 @@ export default declare((api, options) => {
           const exportMap = Object.create(null);
           const modules = [];
 
-          let beforeBody = [];
+          const beforeBody = [];
           const setters = [];
           const sources = [];
           const variableIds = [];
@@ -475,7 +475,7 @@ export default declare((api, options) => {
           }
 
           modules.forEach(function (specifiers) {
-            let setterBody = [];
+            const setterBody = [];
             const target = scope.generateUid(specifiers.key);
 
             for (let specifier of specifiers.imports) {
@@ -540,7 +540,8 @@ export default declare((api, options) => {
                 }
               }
 
-              setterBody = setterBody.concat(
+              Array.prototype.push.apply(
+                setterBody,
                 constructExportCall(
                   path,
                   t.identifier(exportIdent),
@@ -589,7 +590,8 @@ export default declare((api, options) => {
           }
 
           if (exportNames.length) {
-            beforeBody = beforeBody.concat(
+            Array.prototype.push.apply(
+              beforeBody,
               constructExportCall(
                 path,
                 t.identifier(exportIdent),
diff --git a/packages/babel-plugin-transform-parameters/src/rest.js b/packages/babel-plugin-transform-parameters/src/rest.js
index cfba76ce4ae4..5cf051185d99 100644
--- a/packages/babel-plugin-transform-parameters/src/rest.js
+++ b/packages/babel-plugin-transform-parameters/src/rest.js
@@ -305,7 +305,8 @@ export default function convertFunctionRest(path) {
     return true;
   }
 
-  state.references = state.references.concat(
+  Array.prototype.push.apply(
+    state.references,
     state.candidates.map(({ path }) => path),
   );
 
diff --git a/packages/babel-traverse/src/path/family.ts b/packages/babel-traverse/src/path/family.ts
index 83701952361b..f1c45a2a1b30 100644
--- a/packages/babel-traverse/src/path/family.ts
+++ b/packages/babel-traverse/src/path/family.ts
@@ -46,7 +46,9 @@ function addCompletionRecords(
   records: Completion[],
   context: CompletionContext,
 ): Completion[] {
-  if (path) return records.concat(_getCompletionRecords(path, context));
+  if (path) {
+    Array.prototype.push.apply(records, _getCompletionRecords(path, context));
+  }
   return records;
 }
 
@@ -73,9 +75,9 @@ function completionRecordForSwitch(
     if (normalCompletions.length) {
       lastNormalCompletions = normalCompletions;
     }
-    records = records.concat(breakCompletions);
+    Array.prototype.push.apply(records, breakCompletions);
   }
-  records = records.concat(lastNormalCompletions);
+  Array.prototype.push.apply(records, lastNormalCompletions);
   return records;
 }
 
@@ -117,7 +119,7 @@ function getStatementListCompletion(
   paths: NodePath[],
   context: CompletionContext,
 ): Completion[] {
-  let completions = [];
+  const completions = [];
   if (context.canHaveBreak) {
     let lastNormalCompletions = [];
     for (let i = 0; i < paths.length; i++) {
@@ -155,11 +157,11 @@ function getStatementListCompletion(
           // When we have seen normal completions from the last statement
           // it is safe to stop populating break and mark normal completions as break
           normalCompletionToBreak(lastNormalCompletions);
-          completions = completions.concat(lastNormalCompletions);
+          Array.prototype.push.apply(completions, lastNormalCompletions);
           // Declarations have empty completion record, however they can not be nested
           // directly in return statement, i.e. `return (var a = 1)` is invalid.
           if (lastNormalCompletions.some(c => c.path.isDeclaration())) {
-            completions = completions.concat(statementCompletions);
+            Array.prototype.push.apply(completions, statementCompletions);
             replaceBreakStatementInBreakCompletion(
               statementCompletions,
               /* reachable */ true,
@@ -170,7 +172,7 @@ function getStatementListCompletion(
             /* reachable */ false,
           );
         } else {
-          completions = completions.concat(statementCompletions);
+          Array.prototype.push.apply(completions, statementCompletions);
           if (!context.shouldPopulateBreak) {
             replaceBreakStatementInBreakCompletion(
               statementCompletions,
@@ -181,9 +183,10 @@ function getStatementListCompletion(
         break;
       }
       if (i === paths.length - 1) {
-        completions = completions.concat(statementCompletions);
+        Array.prototype.push.apply(completions, statementCompletions);
       } else {
-        completions = completions.concat(
+        Array.prototype.push.apply(
+          completions,
           statementCompletions.filter(c => c.type === BREAK_COMPLETION),
         );
         lastNormalCompletions = statementCompletions.filter(
@@ -202,7 +205,7 @@ function getStatementListCompletion(
         (pathCompletions.length === 1 &&
           !pathCompletions[0].path.isVariableDeclaration())
       ) {
-        completions = completions.concat(pathCompletions);
+        Array.prototype.push.apply(completions, pathCompletions);
         break;
       }
     }
@@ -227,7 +230,8 @@ function _getCompletionRecords(
     // @ts-expect-error(flow->ts): todo
     records = addCompletionRecords(path.get("body"), records, context);
   } else if (path.isProgram() || path.isBlockStatement()) {
-    records = records.concat(
+    Array.prototype.push.apply(
+      records,
       // @ts-expect-error(flow->ts): todo
       getStatementListCompletion(path.get("body"), context),
     );
@@ -241,7 +245,8 @@ function _getCompletionRecords(
   } else if (path.isSwitchStatement()) {
     records = completionRecordForSwitch(path.get("cases"), records, context);
   } else if (path.isSwitchCase()) {
-    records = records.concat(
+    Array.prototype.push.apply(
+      records,
       getStatementListCompletion(path.get("consequent"), {
         canHaveBreak: true,
         shouldPopulateBreak: false,
@@ -451,7 +456,7 @@ export function getBindingIdentifierPaths(
   [x: string]: NodePath;
 } {
   const path = this;
-  let search = [].concat(path);
+  const search = [path];
   const ids = Object.create(null);
 
   while (search.length) {
@@ -493,8 +498,10 @@ export function getBindingIdentifierPaths(
       for (let i = 0; i < keys.length; i++) {
         const key = keys[i];
         const child = id.get(key);
-        if (Array.isArray(child) || child.node) {
-          search = search.concat(child);
+        if (Array.isArray(child)) {
+          Array.prototype.push.apply(search, child);
+        } else if (child.node) {
+          search.push(child);
         }
       }
     }
diff --git a/packages/babel-traverse/src/path/inference/inferer-reference.ts b/packages/babel-traverse/src/path/inference/inferer-reference.ts
index fc745dd14344..71441dbe39c7 100644
--- a/packages/babel-traverse/src/path/inference/inferer-reference.ts
+++ b/packages/babel-traverse/src/path/inference/inferer-reference.ts
@@ -84,7 +84,7 @@ function getTypeAnnotationBindingConstantViolations(binding, path, name) {
     }*/
 
     // add back on function constant violations since we can't track calls
-    constantViolations = constantViolations.concat(functionConstantViolations);
+    Array.prototype.push.apply(constantViolations, functionConstantViolations);
 
     // push on inferred types of violated paths
     for (const violation of constantViolations) {
diff --git a/packages/babel-types/src/comments/addComments.ts b/packages/babel-types/src/comments/addComments.ts
index 7aba0779766b..294e3d9a4e58 100644
--- a/packages/babel-types/src/comments/addComments.ts
+++ b/packages/babel-types/src/comments/addComments.ts
@@ -16,7 +16,7 @@ export default function addComments<T extends t.Node>(
     if (type === "leading") {
       node[key] = comments.concat(node[key]);
     } else {
-      node[key] = node[key].concat(comments);
+      Array.prototype.push.apply(node[key], comments);
     }
   } else {
     node[key] = comments;
diff --git a/packages/babel-types/src/modifications/flow/removeTypeDuplicates.ts b/packages/babel-types/src/modifications/flow/removeTypeDuplicates.ts
index dbe07300fa32..ff75c19e7704 100644
--- a/packages/babel-types/src/modifications/flow/removeTypeDuplicates.ts
+++ b/packages/babel-types/src/modifications/flow/removeTypeDuplicates.ts
@@ -48,7 +48,7 @@ export default function removeTypeDuplicates(
 
     if (isUnionTypeAnnotation(node)) {
       if (typeGroups.indexOf(node.types) < 0) {
-        nodes = nodes.concat(node.types);
+        Array.prototype.push.apply(nodes, node.types);
         typeGroups.push(node.types);
       }
       continue;
diff --git a/packages/babel-types/src/modifications/typescript/removeTypeDuplicates.ts b/packages/babel-types/src/modifications/typescript/removeTypeDuplicates.ts
index b418dafc4b42..18bc7334bbe8 100644
--- a/packages/babel-types/src/modifications/typescript/removeTypeDuplicates.ts
+++ b/packages/babel-types/src/modifications/typescript/removeTypeDuplicates.ts
@@ -41,7 +41,7 @@ export default function removeTypeDuplicates(
 
     if (isTSUnionType(node)) {
       if (typeGroups.indexOf(node.types) < 0) {
-        nodes = nodes.concat(node.types);
+        Array.prototype.push.apply(nodes, node.types);
         typeGroups.push(node.types);
       }
       continue;