Description
With both "IntelliSense for CSS class names" and "Angular Language Service" enabled, following happened.
Starting VS Code in a pretty basic test project spawns a VSC process that continues to increase memory consumption at 10-13% CPU load (i7-6800K) ultimately resulting in ALS repoting "JavaScript heap out of memory".
Closing VS Code does not kill the process, but leaves it running at CPU load and memory fluctuating around 2-3 GB.
Disabling Angular Language Service makes everything else work.
Disabling IntelliSense for CSS class names makes everything else work.
When adding IntelliSense for CSS class names, the output for ALS shows
Search path: c:/1work/Programming/angular2/routing-start/node_modules/clone
Full ALS log with IntelliSense for CSS class names (autocomplete/intellisense never works for anything)
Search path: c:/1work/Programming/angular2/routing-start/src/app/servers
Config file name: c:/1work/Programming/angular2/routing-start/src/tsconfig.json
Angular Language Service: 5.0.0-beta.5
TypeScript: 2.4.2
getTemplateRefrences: 818ms
Add recursive watcher for: c:/1work/Programming/angular2/routing-start/src
Opened configuration file c:/1work/Programming/angular2/routing-start/src/tsconfig.json
getTemplateRefrences: 0ms
Search path: c:/1work/Programming/angular2/routing-start/node_modules/clone
Config file name: c:/1work/Programming/angular2/routing-start/tsconfig.json
Angular Language Service: 5.0.0-beta.5
TypeScript: 2.4.2
getTemplateRefrences: 632ms
Add recursive watcher for: c:/1work/Programming/angular2/routing-start
Opened configuration file c:/1work/Programming/angular2/routing-start/tsconfig.json
getTemplateRefrences: 0ms
getTemplateRefrences: 0ms
Angular Language Service: 5.0.0-beta.5
TypeScript: 2.4.2
getTemplateRefrences: 105ms
Search path: c:/1work/Programming/angular2/routing-start/src/app
Config file name: c:/1work/Programming/angular2/routing-start/src/tsconfig.json
getTemplateRefrences: 0ms
getTemplateRefrences: 0ms
FATAL ERROR: CALL_AND_RETRY_LAST Allocation failed - JavaScript heap out of memory
Full ALS log without IntelliSense for CSS class names (autocomplete/intellisense works at startup)
Search path: c:/1work/Programming/angular2/routing-start/src/app/servers
Config file name: c:/1work/Programming/angular2/routing-start/src/tsconfig.json
Angular Language Service: 5.0.0-beta.5
TypeScript: 2.4.2
getTemplateRefrences: 711ms
Add recursive watcher for: c:/1work/Programming/angular2/routing-start/src
Opened configuration file c:/1work/Programming/angular2/routing-start/src/tsconfig.json
getTemplateRefrences: 0ms
getDiagnostics: 43ms
Note that, there is an similar issue breaking the Polymer/vscode-plugin, so the "fault" is probably in here.