This document will help explain datapoints and graphs in the AJAX Load Time tab of a RUM report. This is a companion document for RUM, and is best used once you have generated a RUM snippet and are actively collecting data.
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AJAX Load Time Trend
AJAX calls are counted separately from page views because they can affect components after a load event is fired. For example, adding an item to a shopping cart requires a request and a response. The data volume of an AJAX request tends to be smaller than the assets loading, so first byte and AJAX load time will generally be much lower than First Paint or Time to Interactive (TTI) metrics.
It’s also possible that static sites may have no AJAX load time.
The AJAX load time trend graph displays data points for total number of Ajax calls, first byte, and Ajax load against the baseline and allows you to observe slow payloads. Spikes higher than 1000 ms (around 1 second), may indicate a performance issue.
AJAX Load Time Distribution
AJAX load time distribution is a measure of the distribution of users who are experiencing a range of load times. This metric is not affected by APDEX threshold. Hover over a bar to see the number of users that experience a specific AJAX load time on average.
AJAX Load Time Breakdown
The AJAX load time breakdown is a bar graph that helps visualize the performance of AJAX calls, using the Server and Transfer datapoints as the primary metric(s). The date range selected is compared to a baseline of the previous week’s worth of data.
Connection: This represents the time it takes to perform a DNS lookup, establish the connection and send the web page request.
Server: This represents the time it takes the server to process the request and initiate a response.
Transfer: This value represents the time it takes for the browser to download the AJAX response.