Firefox takes a long time to start up

[Tubelerczyk]

After upgrading to version 135, Firefox started to launch more slowly. Previously it would launch almost instantly for me, but now the launch process freezes for about 5 seconds, and freezes for about 3 seconds after launching. Using Firefox is therefore only possible after about 8 seconds. Before version 135, Firefox was ready to go in 2 seconds.
I have cleaned everything that can be cleaned in the browser, but this has not affected the start-up speed of the browser in any way.
Firefox, instead of moving forward, is regressing.

Windows 11 Pro 24H2
Operating system compilation: 26100.3194

[siffemcon · Accepted solution]

Try FF menu > Help > More Troubleshooting Information > Clear startup cache button.

[siffemcon · Accepted solution]

Try FF menu > Help > More Troubleshooting Information > Clear startup cache button.

[Tubelerczyk]

Many thanks. This actually solved the problem.
🇵🇱

[Tubelerczyk]

There is, however, a problem. I have to carry out this operation, after every reboot, because the problem recurs.

[siffemcon]

See if clearing the browser cache helps:

- press Ctrl-Shift-Delete (Mac: Cmd-Shift-Delete)

- set 'Time range...' to 'Everything'

- untick all items except 'Temporary cached files and pages'

- clear, then restart FF

[Tubelerczyk]

There was one word missing from the previous post and you may have understood it as having to repeat the operation every time you restart Firefox.
It should be: I have to repeat this operation every time I restart Windows 11.

[Tubelerczyk]

That Firefox cache cleanup did help, though. The cause of the start-up delays was rooted in the services. Some system services have a delayed start-up setting. Probably, one of these services has the effect of taking a little longer for programs to start before it starts.
Once all the services have started up, Firefox already starts up normally.

[siffemcon]

Yup. I always give the OS plenty of time to boot up before trying to start apps other than File Explorer.

[Tubelerczyk · Accepted solution]

After much testing, it turned out that NORTON 360 antivirus is responsible for these delays.

[siffemcon]

Ugh, lose that garbage and use Defender.