Flickering Effect with Nginx Pagespeed on fonts

[jonathan maderer]

Hey, since i use Pagespeed on Nginx (before Apache) i notice some real bad flickering effects with Fonts, i cant figure out what it is and where it come from. If i clear the cache of pagespeed it took 2-4 Hours and its back.
I hope someone could tell me the reason for that and maybe if i missconfigured something.


Here is some example, if you load the site you can see that the font is flickering a lot of times up and down, also on every refresh (Firefox 36.0.1).

https://gnetwork.eu/?hash=5e68f9c6eabcf4c35a96fb4ea16220c8&lang=de

Currently my options are.

Filters
ah	Add Head
cw	Collapse Whitespace
cc	Combine Css
jc	Combine Javascript
gp	Convert Gif to Png
jp	Convert Jpeg to Progressive
jw	Convert Jpeg To Webp
mc	Convert Meta Tags
pj	Convert Png to Jpeg
dd	Dedup Inlined Images
ea	Elide Attributes
ec	Cache Extend Css
ei	Cache Extend Images
es	Cache Extend Scripts
fc	Fallback Rewrite Css 
if	Flatten CSS Imports
hw	Flushes html
ci	Inline Css
gf	Inline Google Font CSS
ii	Inline Images
il	Inline @import to Link
ji	Inline Javascript
id	Insert Image Dimensions
js	Jpeg Subsampling
ll	Lazyload Images
cj	Move Css Above Scripts
pr	Prioritize Critical Css
rj	Recompress Jpeg
rp	Recompress Png
rw	Recompress Webp
rc	Remove Comments
ri	Resize Images
ir	Resize to Rendered Image Dimensions
cf	Rewrite Css
jm	Rewrite External Javascript
jj	Rewrite Inline Javascript
cu	Rewrite Style Attributes With Url
is	Sprite Images
cp	Strip Image Color Profiles
md	Strip Image Meta Data

Options
  AdminPath (nap)                              /pagespeed_admin
  AvoidRenamingIntrospectiveJavascript (aris)  True
  BeaconUrl (bu)                               /ngx_pagespeed_beacon
  CacheFlushPollIntervalSec (acfpi)            5
  ConsolePath (ncp)                            /pagespeed_console
  DefaultSharedMemoryCacheKB (dsmc)            1900000
  EnableCachePurge (euci)                      True
  EnableRewriting (e)                          1
  FetchHttps (fhs)                             enable
  FileCacheCleanIntervalMs (afcci)             3600000
  FileCacheInodeLimit (afcl)                   500000
  FileCachePath (afcp)                         /var/ngx_pagespeed_cache
  FileCacheSizeKb (afc)                        102400
  GlobalAdminPath (ngap)                       /pagespeed_global_admin
  GlobalStatisticsPath (ngsp)                  /ngx_pagespeed_global_statistics
  InPlaceResourceOptimization (ipro)           True
  LRUCacheByteLimit (alcb)                     16384
  LRUCacheKbPerProcess (alcp)                  8192
  MemcachedServers (ams)                       127.0.0.1:11211
  MessagesPath (nmp)                           /ngx_pagespeed_message
  PurgeMethod (pm)                             PURGE
  RespectXForwardedProto (rxfp)                True
  RewriteLevel (l)                             Core Filters
  StatisticsPath (nsp)                         /ngx_pagespeed_statistics

[Jeff Kaufman]

I tested this just now in Chrome and Firefox and I'm not seeing any
flickering. But maybe I'm not understanding what you mean? Could you
maybe take a screencast of the problem and share that?

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[jonathan maderer]

Hi Jeff, here is a screencast of it
http://www.screencast-o-matic.com/watch/coe6IZedtT

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[Jeff Kaufman]

Thanks for the screencast! Now that I know what I'm looking for I see
it as well in FireFox. Looking into it.

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[Jeff Kaufman]

I'm seeing this font flickering issue even if I turn off PageSpeed
with a query param:

https://gnetwork.eu/?hash=3818e17ce167d7efe1cef9350b2ae8ff&lang=de&PageSpeed=off

Could you try commenting out all the pagespeed directives in your
configuration and seeing whether it still happens? I think the
problem may not actually be with PageSpeed.

[jonathan maderer]

Hi Jeff, i will try this. But i also think the var PageSpeed=off hasn't any effect. I still can see the header.
I will need some time to get the results, the issue will only appear after several hours. I start now to cut off some filters and see when it would disappear.

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[Jeff Kaufman]

PageSpeed=off seems to have an effect to me: when I look at your
source normally (with pagespeed on) I see things like
pagespeed.CriticalImages.checkImageForCriticality while when I add
&PageSpeed=off I don't see any references to pagespeed in the source
or the header.

On Tue, Mar 10, 2015 at 11:54 AM, jonathan maderer

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