Avoid bottleneck requests


This audit identifies long-running requests that are blocking the first ad request. These are requests that were initiated and which also received a response before the first ad request was made. Reducing the number and duration of these blocking requests will reduce the latency of the first ad request, speeding up ad loading.


The details of this audit contain the top 5 blocking requests (by cost). The goal here is to remove or reduce the duration of these requests to speed up ad loading. Some tips for doing this include:

  • Eliminating unnecessary requests.
  • Deferring non-critical requests until after ads are loaded.
  • Issuing requests in parallel rather than serially.
  • Improving response times by optimizing backend services, using HTTP/2, etc.

More information

This audit displays the top 5 bottleneck requests by cost. The cost of a request is computed as follows:

request duration + (request self-time * 3)

Where request self-time is equal to duration minus time spent blocked by other requests. Only requests with a self-time greater than 250ms or a duration greater than 1s are considered.