The Performance interface provides access to performance-related
for the current page. It's part of the High Resolution Time API,
is enhanced by the Performance Timeline API, the Navigation Timing
the User Timing API, and the Resource Timing API.

Performance Events.

The PerformanceEntry object encapsulates a single performance
that is part of the performance timeline. A performance entry
be directly created by making a performance `web.mark` or `web.measure`
example by calling the `web.mark()` method) at an explicit point
an application. Performance entries are also created in indirect
such as loading a resource (such as an image).

PerformanceFrameTiming is an abstract interface that provides
timing data about the browser's event loop.

The PerformanceLongTaskTiming interface of the the Long Tasks
reports instances of long tasks.

PerformanceMark is an abstract interface for `performance.PerformanceEntry`
with an `web.entryType` of \"mark\". Entries of this type are
by calling `web.performance.mark()` to add a named `dom.DOMHighResTimeStamp`
mark) to the browser's performance timeline.

PerformanceMeasure is an abstract interface for `performance.PerformanceEntry`
with an `web.entryType` of \"measure\". Entries of this type
created by calling `web.performance.measure()` to add a named
(the measure) between two marks to the browser's performance

The legacy PerformanceNavigation interface represents information
how the navigation to the current document was done.

The PerformanceNavigationTiming interface provides methods and
to store and retrieve metrics regarding the browser's document
events. For example, this interface can be used to determine
much time it takes to load or unload a document.

The PerformanceObserver interface is used to observe performance
events and be notified of new performance entries as they are
in the browser's performance timeline.

The PerformanceObserverEntryList interface is a list of peformance
that were explicitly observed via the `web.observe()` method.

The PerformancePaintTiming interface of the Paint Timing provides
information about \"paint\" (also called \"render\") operations
web page construction. \"Paint\" refers to conversion of the
tree to on-screen pixels.

The PerformanceResourceTiming interface enables retrieval and
of detailed network timing data regarding the loading of an application's
An application can use the timing metrics to determine, for example,
length of time it takes to fetch a specific resource, such as
`xml.XMLHttpRequest`, `web.<SVG>`, image, or script.

The PerformanceServerTiming interface surfaces server metrics
are sent with the response in the `web.Server-Timing` HTTP header.

The PerformanceTiming interface is a legacy interface kept for
compatibility and contains properties that offer performance
information for various events which occur during the loading
use of the current page. You get a PerformanceTiming object describing
page using the `web.window.performance.timing` property.