ubuntu-sdk-bugs team mailing list archive

[Olivier Tilloy <olivier.tilloy@xxxxxxxxxxxxx>]

On my beefy laptop, when opening a new tab, the UrlGridView for the list
of top sites in the new tab view takes ~250ms to instantiate, of which
almost half the time (115ms) is for instantiating the Loader that
contains one Favicon.

After moving away the favicons cache folder, instantiating the favicons
is almost instantaneous (they are being re-downloaded on a different
thread), and instantiating the UrlGridView is down to 170ms, which is
still expensive, but better.

I instrumented the favicon fetcher code, and the culprit seems to be the
first icon being downloaded (usually because the favicon doesn’t
actually exist, but we’re not tracking that, so we try to download it
anyway because it hasn’t been cached on disk). Specifically, on my
laptop instantiating the first QNetworkAccessManager takes ~100ms. One
QNAM is being instantiated for each favicon that we fetch from the
network, but the subsequent instantiations are free, only the first one
is expensive. This would need some further investigation in Qt itself.

One optimization we could try to apply is to cache an empty file on disk
for non-existent favicons, in order to avoid trying to re-download them
over and over again.

** Changed in: webbrowser-app (Ubuntu)
   Importance: Undecided => High

** Changed in: webbrowser-app (Ubuntu)
     Assignee: (unassigned) => Olivier Tilloy (osomon)

** Also affects: qtbase-opensource-src (Ubuntu)
   Importance: Undecided
       Status: New

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https://bugs.launchpad.net/bugs/1585285

Title:
  Creating or switching to a new tab feels slow

Status in qtbase-opensource-src package in Ubuntu:
  New
Status in webbrowser-app package in Ubuntu:
  Confirmed

Bug description:
  bq M10 rc-proposed r112

  Steps to reproduce:
  1. Open few tabs with websites
  2. Click 'New tab' button

  Expected result:
  Browser creates new tab and switches to it immediately.

  What happens instead:
  New tab is created and browser switches to it after about 2-3 seconds. Long enough to makes me worried if everything is fine with it.

  Similar situation is when I have a 'new tab' already opened as a
  background tab. When I switch to it from a tab with a webpage, the
  action is taking too long.

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