Disable intellij indexing on specific folder

Question

Mark this folder as Excluded in the File | Project Structure | Modules | Sources tab.

Edit: also make sure it's not added as a library in the project.

On IntelliJ 13+ (don't know for earlier versions), you can right click on a folder > Mark Directory As > Excluded.

if you cannot do it throu the Modules menu because your intellij freezes (like in my case) edit .iml file of your projet and add excludeFolder line as below:

<content url="file://$MODULE_DIR$">
  <sourceFolder url="file://$MODULE_DIR$/src/main/java" isTestSource="false" />
  <sourceFolder url="file://$MODULE_DIR$/src/main/resources" type="java-resource" />
  <sourceFolder url="file://$MODULE_DIR$/src/test/features" type="java-test-resource" />
  <sourceFolder url="file://$MODULE_DIR$/src/test/java" isTestSource="true" />
  <sourceFolder url="file://$MODULE_DIR$/src/test/resources" type="java-test-resource" />
  <excludeFolder url="file://$MODULE_DIR$/node_modules" />
  <excludeFolder url="file://$MODULE_DIR$/target" />
</content>

The option is now called Stop/Start Index, available from the folder context menu in solution explorer. When index is stopped, the folder will appear with "no index" annotation on the right.

I excluded the build output folder and no longer getting lengthy index refreshes after each build. Also full text search is a lot faster (near instant).