1600092 - Showing network errors is extremely slow (6+s of parent process jank)

Status: NEW

(DevTools :: Netmonitor, defect, P3)

Description

[Florian Quèze [:florian]]

Someone just told me he can't use Firefox for webdevelopment because devtools are slow. He captured this profile for me: https://perfht.ml/34vOC51

Most of the time is in resource://devtools/client/shared/components/tree/TreeView.js

Comment 1

[Jan Honza Odvarko [:Honza] (always need-info? me)]

Thanks for the report Florian!
Honza

Comment 2

[Julian Descottes [:jdescottes]]

Attachment: buddysystem.local_Archive [19-11-28 16-33-59].har

Quickly tested with the HAR in attachment here.

• open netmonitor
• import har
• select error request in the list
• select "Response" side panel

In Firefox 71, this is almost instant on my machine, while on current Release (FF70), it can take up to 2 seconds and even beach ball. So it seems we have somehow fixed part of this issue recently, but it would be nice to know why/how.

In both versions, the response tab shows only "Preview" and "Payload" sections.