Why is my ember-cli build time so slow on windows?

Question

Ember-cli is building very slowly with ember server on windows.

Build successful - 13126ms.

Slowest Trees                  | Total
-------------------------------+----------------
TreeMerger (vendor)            | 3154ms
TreeMerger (stylesAndVendor)   | 2051ms
TreeMerger (appAndDependencies) | 1914ms
StaticCompiler                 | 1791ms

This is in contrast to the same project building in less that 1 second on a linux box.

Answer 1

There are two big culprits:

1. Real time file system scanning or protection
   • Realtime-protection from Windows Defender (also know as Microsoft Security Essentials in win7)
   • Windows Search Indexing
   • Antivirus scanning
2. Unused files in your bower_components folder

Real time Scanning

During a build numerous files are generate in the ./tmp folder of the ember project, both the indexer and the realtime-protection make additional reads of each file which adds a significant amount of additional file I/O operations.

The fix is to:

• exclude node.exe and/or the ./tmp folder from realtime-protection, and
• exclude the folder from indexing.
• Disable real-time antivirus scanning

This should get your build time down to a couple seconds. Additional speed improvements for Windows are being investigated continuing to be investigated in relation to Broccoli's handling of the build process.

Managing unused bower files

Having lots of files in the bower_components is the biggest culprit.

I wrote up a script, clean-ember-cli.js, that deletes everything but ember-cli dependancies, and anything imported in the Brocfile.js. I'm getting back to around 5 second build times.

Update

Reports are that running console as admin also helps.

Answer 2

Official recommendation from ember-cli to improve its performance on windows

Install ember-cli-windows with node using the below command

npm install -g ember-cli-windows

Run the following command on your project root folder

ember-cli-windows

Answer 3

mind one important thing... and I didn`t found out in any forum... if you are working with a laptop and you are not connected with AC, windows may run in low performance mode to keep battery. This cause ember build proyects 4 times slower