High cpu usage on 01/29 insiders build

[mjbvz]

tsserver.log.zip

TypeScript Version: 2.7.1-insiders-2018.0129

@Tyriar reports high CPU usage when working in the VS Code workspace with the latest insiders. I have attached the logs

tsserver.log.zip

@sheetalkamat Seems like we are scanning node_modules here. Not sure if that is expected. Tail of the logs have a bunch of message of the form:

...
Info 29856[12:4:46.663] DirectoryWatcher recursive:: Elapsed: 30ms Trigger: /Users/daimms/dev/Microsoft/vscode/node_modules/bufferstreams/src/index.js PathInfo: /Users/daimms/dev/Microsoft/vscode/node_modules Project: /Users/daimms/dev/Microsoft/vscode/src/tsconfig.json WatchType: Directory of Failed lookup locations in module resolution
Info 29856[12:4:46.663] DirectoryWatcher recursive:: Trigger: /Users/daimms/dev/Microsoft/vscode/node_modules/bufferstreams/src PathInfo: /Users/daimms/dev/Microsoft/vscode/node_modules Project: /Users/daimms/dev/Microsoft/vscode/src/tsconfig.json WatchType: Directory of Failed lookup locations in module resolution
Info 29856[12:4:46.664] DirectoryWatcher recursive:: Elapsed: 1ms Trigger: /Users/daimms/dev/Microsoft/vscode/node_modules/bufferstreams/src PathInfo: /Users/daimms/dev/Microsoft/vscode/node_modules Project: /Users/daimms/dev/Microsoft/vscode/src/tsconfig.json WatchType: Directory of Failed lookup locations in module resolution
Info 29856[12:4:46.664] DirectoryWatcher recursive:: Trigger: /Users/daimms/dev/Microsoft/vscode/node_modules/bufferstreams PathInfo: /Users/daimms/dev/Microsoft/vscode/node_modules Project: /Users/daimms/dev/Microsoft/vscode/src/tsconfig.json WatchType: Directory of Failed lookup locations in module resolution
Info 29856[12:4:46.664] Scheduled: /Users/daimms/dev/Microsoft/vscode/src/tsconfig.json, Cancelled earlier one
Info 29856[12:4:46.664] Scheduled: *refreshInferredProjects*, Cancelled earlier one
...

[sheetalkamat]

I am not sure why the directory watcher is invoked on the already present source files. We expect that to be file watcher instead. But even apart from that, i think we are spending too much time in isEmittedFile