Browser – Queue Wait

Less critical resources such as images can be put into a queue by the browser and processed later. Plumbr registers such requests under Queue Wait Root Cause if being in the queue phase exceeds the threshold. The reason why it happens is:

• lack of TCP connections
• too many requests are being processed in parallel (usually by default the browser can process 6 requests to the same domain in parallel)
• some requests are postponed because considered by browser not critical

Grouping of Queue Wait Root Causes is done by domain name.

To solve this issue:

• domain sharding could be done.
• reduce the number of requests by:
  • concatenating CSS or JS files together
  • using CSS sprites for images