Global text rendering through userstyle - Slows browser




Extension Compatibility
5 years ago
2 years ago


(Reporter: Naveen, Unassigned)



18 Branch
Windows 7

Firefox Tracking Flags

(Not tracked)




5 years ago
User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:18.0) Gecko/20100101 Firefox/18.0
Build ID: 20130104151925

Steps to reproduce:

Tried to use a global text rendering userstlye with Stylish Add-On.

For eg : 

@namespace html url(;
body, input {text-shadow: 0px 0px 1px #999;}

This is a code by logonaniket for his userstlye : Firefox Strong Font Rendering (Like Safari)

Actual results:

There is significant slowdown of browser in all aspect , like right click , scrool , accessing menu etc.

Expected results:

Not slowdown ?

Comment 1

5 years ago
This userstyle, I guess?

Comment 2

5 years ago

Although there is considerable slowdown of the browser , but why should it happen ? coz i have a good config , and it can and it should render it correctly right , without much slowdown. Also apart from this one global userstyle , any simple style (not global) causes slowdown.
It looks like that style intentionally blurs all text on web pages, with a blur radius of 1px.  Blurring is somewhat CPU-intensive, so it's not surprising that that it impacts browser performance.

A similar effect might be possible without slowing down the browser, by using Microsoft's ClearType Tuner, though I'm not sure it can get the exact effect you want:

Comment 4

5 years ago
Currently i have disabled that global font rendering userstyle. But in general , ANY Userstyle slows the webpage significantly.
(In reply to Naveen from comment #4)
> But in
> general , ANY Userstyle slows the webpage significantly.

Can you give other Examples?
Flags: needinfo?(naveenreloaded)

Comment 6

5 years ago
My userstyle.

there is slight slowdown with this one , although the codes are very small. But for larger one its gets slow.

Also Why does the browser slow when there are many flash elements / pictures in a page ?
Flags: needinfo?(naveenreloaded)

Comment 7

5 years ago
(In reply to Naveen from comment #6)
> My userstyle.

Can you try removing the box-shadow properties from that and see if performance improves? I've seen large box-shadows cause scroll performance issues before.

Comment 8

5 years ago
Yup removing box-shadow improves speed. Is it with rendering or firefox handling of css .. If such a element is causing performance drop , why CSS3 having such element ? Is there a way to improve ?
Naveen can you reproduce this issue using new profile or in safe mode? Because I couldn't repro even with default profile.

Comment 10

5 years ago
Just to stress the browser , you can use my CSS heavy userstlye. , see if this slows down.

Also which specific thing are you trying to reproduce ? then i might try it on fresh profile.

Comment 11

4 years ago
(In reply to Naveen from comment #10)
> Just to stress the browser , you can use my CSS heavy userstlye.
> , see if this slows down.
> Also which specific thing are you trying to reproduce ? then i might try it
> on fresh profile.
Flags: needinfo?(mihai.morar)
Keywords: perf
I've tried reproducing the issue on:
FF 18 release 
Win 7 x64
using the provided style and a new profile. 
I've installed the provided style and browsed reddit with and without the style. No significant performance changes were noticed. 

If you can provide additional information that might help reproducing the issue( eg: addons installed) that might help.
Also try reproducing it on a new profile.
Flags: needinfo?(naveenreloaded)

Comment 13

4 years ago
Can you install RES and check again if there is any slowdown ? I used it with RES
Flags: needinfo?(naveenreloaded)
Tested on the latest release FF 32.0.1 with Res installed not slowdown was experienced.
Flags: needinfo?(mihai.morar)
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:46.0) Gecko/20100101 Firefox/46.0
Build ID: 20160111030207

Works for me also on the latest Nightly 46 - no slowdown after installing RES and navigating reddit. 

Naveen, are you still having the slowdown issue with the latest Firefox versions (current Firefox 43.0.4, Nightly 46)?
Flags: needinfo?(naveenreloaded)

Comment 16

2 years ago
Even though it has improved , but i would still say it lags a bit. More so while scrolling.
Flags: needinfo?(naveenreloaded)

Comment 17

2 years ago
When visiting reddit with RES , there is evident input delay while scrolling.
Component: Untriaged → Extension Compatibility
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