In Lightning, it is important to monitor the complexity of your component hierarchy. While it is good to be componentized for reasons of separation of concerns, too much of it can result in a heavy component tree and result in poor performance. Salesforce provides an excellent tool known as Lightning Inspector, which provides insights into your component hierarchy and the rendering times for each component. You can download and install it from the Google Chrome web store.

The following shows an example screenshot for the FormulaForce application:

You may also have noticed that LEX displays page size and response time in the header:

The preceding diagrams show additional performance information available to developers, showing the page load time and the size of the page. In the next section, we will review the tools used to understand the performance impact the locker service can have on your code.