NestJS startup unbelievably slow in development

Try to set env TS_NODE_TRANSPILE_ONLY=true.

e.g. TS_NODE_TRANSPILE_ONLY=true ts-node -r tsconfig-paths/register src/main.ts

docs: https://github.com/TypeStrong/ts-node#cli-and-programmatic-options

It's speed up my app startup

One option is to use tsc-watch instead of ts-node and nodemon. You can set up the start command in your start:dev as follows:

{  //this is assuming you're building to the dist folder  ...  "start:dev": "tsc-watch --onSuccess \"node dist/main.js\" --onFailure \"echo   There was a problem with the build!\" -p tscfonig.json"   ...}

In my experience I ran into too many problems with ts-node and registering routes, plus load times were killing me. With tsc-watch I get a fresh build of the project, rebuilding only the files that were changed. This way you're also testing that tsc works while developing.

I also use a tsconfig-bootstrap command to import my custom routes (defined in my tsconfig) and add that into my start command with node -r path/to/my/script.js dist/main.js.

Hope this helps you a bit!

install the latest version of the @nestjs/cli, both globally and locally:

$ npm install -g @nestjs/cli$ cd  /some/project/root/folder$ npm install -D @nestjs/cli

replace/make sure you have the below scripts defined in package.json

"build": "nest build","start": "nest start","start:dev": "nest start --watch","start:debug": "nest start --debug --watch",

make sure you have vs code auto attach on

run

npm run start:dev