Safari lagging on HTML5

Discussion in 'Mac OS X Lion (10.7)' started by HikariYuki, Jul 21, 2011.

  1. HikariYuki macrumors regular

    Jun 29, 2009
    Hi has anybody experienced the following symptoms where if you enable HTML5 on youtube in Safari and play a video its super laggy at first then calms down after a while. Also the cpu usage is high due to a process called QTkitserver safari web content?
  2. Therbo macrumors regular

    Mar 25, 2011
    United Kingdom
    Fullscreening a HTML5 video will also blink the screen white, and sometimes stay white.

    Also ClickToFlash docent display the player correctly in fullscreen.
  3. Maxdr, Aug 3, 2011
    Last edited: Aug 3, 2011

    Maxdr macrumors newbie

    Jun 12, 2011
    Yeah, I'm having the same problem here, on a clean install of Lion on my MBP 13 2010. The QTKitServer process instantly goes to ~100% of CPU usage and lags when playing a YouTube video using HTML5. Then, usually after a few seconds of playback it goes back to normal - ~10-15% of CPU usage.
  4. VanZan macrumors member

    Nov 24, 2011
    I'm having the same problem since Youtube changed to the new design (and also HTML5 coding?) a couple of weeks ago. Also noticed that I can no longer download the video using the activity monitor since it apparently streams the vid (?).

    The video lag is terrible (on my brand new iMac) with QTKitServer process above 100% and Safari lagging like hell, often with baseball mouse icon, all for about 48 seconds. When I switch resolutions, it starts all over. Sound however plays fine with few sporadic stuttering.

    Software is all up to date, including Flash (just in case).

    Anyone has any idea wtf could be done? Youtube is a pita to use this way
  5. Dark Dragoon macrumors 6502a

    Dark Dragoon

    Jul 28, 2006
    I'm not sure whats wrong with the official youtube html5 player as I have the same video lag issue. However I fixed it by going to Then click on the Leave the HTML5 trial link. It should then go back to the Flash player, or if you use the youtube5 plugin it'll go back to the youtube5 html5 player (which works fine unlike the youtube one).
  6. VanZan macrumors member

    Nov 24, 2011
    Thank you very much! The lag is gone and also fullscreen works again without workarounds!

    I was totally unaware this was only a test. AFAIR YouTube appeared one day in the new design.

    Amazing that the problem occurs with html5 when actually flash is the pest to cure ...:confused:

    (I have tried the youtube5 plugin but it didn't help)
  7. pspwesty macrumors newbie

    Aug 16, 2010
    I was having the same problem since youtube went to the new design. I have had clicktoflash installed for ages and had that autoload the html5 by default. Youtubes layout change somehow overrode that and loaded their own crappy html5 player. Opted out of the html5 trial on youtube and the clicktoflash player is back, again defaulting to html5. No more lag! :D Youtube needs to get it together.

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