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Updated to version 54 and now drop down lists are slow. Reverted back to older version (52) and same drop down lists work fine.

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Drop down lists that contain a fair amount of data in Firefox 54.0 eats up about 25-35% of the CPU when accessing it. Then the scroll function is really slow w/in the drop down list. However, scrolling via keyboard or mouse seemed to work ok. I can get the drop down list to work briefly when I go to the Troubleshooting Information and select Refresh Firefox. However, when I close the browser and reopen it I'm back to square one.

Reverted back to version 52.0 and the same drop down list loaded quickly w/o the CPU hit and I was able to scroll just fine. Both versions have the exact same add-ons and no plugins installed.

I have edited several things w/in the Options with no luck. Only fix to date is to revert back to an older version.

Thanks for your help.

Drop down lists that contain a fair amount of data in Firefox 54.0 eats up about 25-35% of the CPU when accessing it. Then the scroll function is really slow w/in the drop down list. However, scrolling via keyboard or mouse seemed to work ok. I can get the drop down list to work briefly when I go to the Troubleshooting Information and select Refresh Firefox. However, when I close the browser and reopen it I'm back to square one. Reverted back to version 52.0 and the same drop down list loaded quickly w/o the CPU hit and I was able to scroll just fine. Both versions have the exact same add-ons and no plugins installed. I have edited several things w/in the Options with no luck. Only fix to date is to revert back to an older version. Thanks for your help.

Isisombululo esikhethiwe

This is a minor point, but could be relevant:

A problem was introduced a few versions ago that sites' style rules for the <option>s of a <select> control were ignored when multiprocess was enabled (which it is for most users). The first round of fixes to restore that functionality that were released in Firefox 54.

By contrast, this may have broader implications:

One of the main technical changes in Firefox 54 was to enable more individual content processes. In Firefox 48-53, the Firefox multiprocess feature would create one process for the UI and one process for content. Now Firefox will aim for four content processes. Perhaps this is an unexpected side effect of this change??

You could try rolling back the number of content processes to 1. If this doesn't work, you may need to revert to single-process mode. Here's how you can try this:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful.

(2) In the search box above the list, type or paste ipc and pause while the list is filtered

(3) If the dom.ipc.processCount preference is bolded and "user set" to 4, double-click it and edit the value to 1, then click OK

Presumably that will not take effect until the next startup, at which time you should check it to make sure it hasn't reverted back. Any difference?

Alternately, you can disable multiprocess mode using a different preference:

(4) In the search box above the list, type or paste autos and pause while the list is filtered

(5) Double-click the browser.tabs.remote.autostart.2 preference to switch the value from true to false

Note: the exact name of the preference may vary, but it will start with browser.tabs.remote.autostart

At your next Firefox startup, it should run in the traditional way. Any difference?

Funda le mpendulo ngokuhambisana nalesi sihloko 👍 8

All Replies (5)

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Is this happening on a particular site, or any page which has a select (dropdown) with many options?

Is there a number of options that triggers the slowness that you are seeing?

It would be worthwhile to set up a CodePen with some test cases?

-- Ereh

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It appears there is a combination of FF version 54, large select list, and going through a VPN.

If accessing the select list outside of the VPN it works fine.

If I revert back to version 52 and connected through the VPN the select list works fine as well.

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Oh, that's useful to know! Thanks.

Next question would be how that select list is populated.

If it's slower on VPN that would make it sound like it's using fetch or XHR to load the options.

It's not immediately obvious how VPN would explain the scrolling issue.

-- Ereh

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Isisombululo Esikhethiwe

This is a minor point, but could be relevant:

A problem was introduced a few versions ago that sites' style rules for the <option>s of a <select> control were ignored when multiprocess was enabled (which it is for most users). The first round of fixes to restore that functionality that were released in Firefox 54.

By contrast, this may have broader implications:

One of the main technical changes in Firefox 54 was to enable more individual content processes. In Firefox 48-53, the Firefox multiprocess feature would create one process for the UI and one process for content. Now Firefox will aim for four content processes. Perhaps this is an unexpected side effect of this change??

You could try rolling back the number of content processes to 1. If this doesn't work, you may need to revert to single-process mode. Here's how you can try this:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful.

(2) In the search box above the list, type or paste ipc and pause while the list is filtered

(3) If the dom.ipc.processCount preference is bolded and "user set" to 4, double-click it and edit the value to 1, then click OK

Presumably that will not take effect until the next startup, at which time you should check it to make sure it hasn't reverted back. Any difference?

Alternately, you can disable multiprocess mode using a different preference:

(4) In the search box above the list, type or paste autos and pause while the list is filtered

(5) Double-click the browser.tabs.remote.autostart.2 preference to switch the value from true to false

Note: the exact name of the preference may vary, but it will start with browser.tabs.remote.autostart

At your next Firefox startup, it should run in the traditional way. Any difference?

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jscher2000,

That did the trick! Steps 1-3 reverted back to count of 4 after reopening the browser but steps 4 and 5 worked.

I appreciated everyone's help with this.

Thanks.