In first Opera 43 developer blog post we announced new feature coming in: Address bar speculative prerenderer. Here are some more details:

When you browse the web a lot of time is spent waiting for pages to load and a lot of energy has gone into optimizing page load, both from browser makers and from site makers. Today that is highly optimized and it is hard to make big improvements.

So let us think outside the box, what is the best way to complete a task earlier? To start earlier! And that is the whole trick in the “prerendering” feature.


There are two ways we can predict what page the user will soon load. When the current page tells us so, and when we can determine from the users actions that they are about to load something.

Pages can use the < link rel=prerender … > tag, and for instance Google uses that for search results if they are pretty sure of what you will load next.

When someone writes in the address bar they are humanly slow. Sometimes it is obvious what they will write after just 1-2 characters but they will just keep writing or arrowing through suggestions for millions or billions of wasted clock cycles.


We expect this feature to results in an average of 1 second faster loads from the address bar. That means that instant page loads become much more common. Of course this depends a lot on how predictable the user is and how fast the user is. I expect you who read this to benefit less than the average user, but I might be wrong.


We try hard to not load anything that would be bad to load. Should you notice anything else, let us know right away!

There are also settings in the privacy section to disable this completely.


If you want to see how predictable you are, fire up Opera, browse some, then load opera:predictors and see what green lines there are (that is when we “know” what you are about to do). You can also look at the prerender section in opera:net-internals and see when we are prerendering right now and historically.


Some studies indicate about 80% of prerendered pages become used, which means that 20% of the prerender page loads are for nothing and has wasted electrons. Therefore we don’t do this in battery saving mode (could argue that we should still do it).

Since every preload (currently) needs to spawn a new process, it also won’t work if you have reached the process limit. Or if you are not predictable enough in your use of the address bar.

Other changes

Chromium was update to version 56.0.2914.3.

Full changelog

Installation links:

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  • L33t4opera

    Hi Daniel, thanks for the new update, and fixes 😉

    New flags:
    – opera:flags#enable-generic-sensor (previously Mac only, now available also for Windows and Linux)

    – opera:flags#permission-prompt-persistence-toggle (Windows, Linux)
    Whether to display a persistence toggle in permission prompts.

    – opera:flags#media-windows-mf-demuxer (Windows)
    Enable MFDemuxer on Windows to support HW accelerated video decoding for non-MSE videos.

    – opera:flags#external-apps-link-filtering (Windows)
    Enable to ask before opening links from untrusted external applications at Opera startup.

  • Ralf Brinkmann

    The flash video still does not play. Flash enabled, “Allow websites to play flash” is enabled, opera://flags/?search=flash#prefer-html-over-flash is disabled.
    Operax64 (standalone installation)
    HWA enabled
    uBlock origin enabled

    • aBallerDotCom

      uBlock Origin is the killer there. I can tell you that from my first hand experience. That is the reason why I’m using Opera now.

      I’m running on a Mac and my popup blockers were killing my Flash video. They just would not load with any browser that had uBlock installed. When I switched over to Opera I had no extensions enabled and everything worked fine. Disabling it did nothing for me which was very weird. It’s just one of those things that we are going to have to deal with now. Websites don’t want us using popup blockers so what they do is refuse us full access to their site if they see we have one installed.

      • Ralf Brinkmann

        No, it isn’t. I have tried to disable uBlock Origin and Ghostery and the video doesn’t play. I have restarted Opera with a complete new and virgin profile, without any extension installed, and the video doesn’t play.

  • Vikruntasas

    Nice, keep up with innovations and built-in features that other browsers don’t have.

    But please fix the memory leak in the VPN. I just can’t use it!

    • helsten2

      Is VPN working for you?

      If I try, VPN just sits there “Connecting …” forever.

      And I only have “Netherlands” available as location. There used to be more options ….
      It has been like this for me for quite a few versions now. I thought it was a known issue. (It worked fine in the beginning …)

      • Working for me, all locations.
        Edit: Oh, but I’m on the stable version…

      • Vikruntasas

        Works fine for me in Win7 64 bit. The connection part that is. But using it is not fun when you get all your RAM taken away. 6 builds later this bug is still there

        • helsten2

          Wonder why it doesn’t work here….

          (also Win7x64)

          I cleared my profile. That fixed the problem ….

  • Юлия

    Private window borders are too thick


  • Gordon Freeman

    Hello Daniel !
    Did you change something while watching videos in fullscreen ?
    Now for every website Opera ask first for permission to show in fullscreen or not. Browser can remember your choice of course but it is unnecessary !

    • Leonardo Gomes

      Haven’t it been working this way since a while?

      • Gordon Freeman

        Yes, but till now the extension “Auto Allow Fullscreen”
        automatically allows fullscreen mode without asking for it.
        So i think they changed something – to the bad.

        • There had been some changes to fullscreen mode that came to us with recent intake. Extension not working anymore is probably bug caused by this. Reported DNA-58341 for it for further investigation.

          • aBallerDotCom

            Is there no way to give users the option if they want to see this alert or not? Reason why I ask is because I don’t see what good it does besides being a nuisance to me personally. There should be an option in the browser to turn this alert off completely. I don’t have any issues with anything going into fullscreen without me click on it to do so. There are no popups that load in fullscreen, I have never seen those. Only popups that are a threat are the ones that load behind my current window and the fullscreen alert does not prevent those.

    • L33t4opera
      • Gordon Freeman

        Hello L33t4opera
        Thank you for your info !
        I thought i was protected by Opera itself.
        Settings > Privacy & security > Protect me from malicious sites

  • NoName

    Yay, I can now move the Opera window with Windows shortcuts again! Thanks.

    Which option disable the prerender/prediction? I can’t seem to find it, and it’s active.

    • Kornelia

      In Settings – Privacy & Security- ‘Predict network actions to improve page load performance’

      • NoName

        But that is already turned off, and it still creates hits and misses in opera://predictors/

        • Leonardo Gomes

          I guess it disables pages being pre-loaded, the list will always be created /modified.

          • NoName

            That’s what I thought too.
            But that also means, that it logs my behavior, when disabled!

            Edit: And “Clear browser data” does not clear this.

          • It’s known issue DNA-58274 “chrome://predictors/ database cannot be cleared by clearing browsing data until after a restart”.

  • Nan

    Hm…What’s wrong with it? Maybe it is a problem that I can’t install update automatically?

  • opera://about/ page crashed (out of memory) after update (on first load of this build)


  • sgrandin

    “So let us think outside the box, what is the best way to complete a task earlier? To start earlier!”

    You just speeded up Opera with the x64 version, and that’s been successful, here at least. Now, how about thinking outside the current Opera developers’ box: give users a tab bar placement option, which would allow us to put the bar in the location that allows for faster work.

    • Ari

      How did you measure the performance improvement against x64 version?

  • iwod

    “So let us think outside the box, what is the best way to complete a task earlier? To start earlier!”

    How about thinking outside the box, and give us Tab Stack or Tab Overflow.

    • Marc

      I really don’t understand why they wouldn’t implement tab stacking…

      • iwod

        I used to think they limit the Tab for resources reason. Forcing you to close tab. But my experience is that it doesnt work. I am now opening more Windows to cope with those tiny Tabs. And there is no easy way to organizes tabs within all these windows.

        • Marc

          My guess is that they think tab stacking is redundant since they implemented pinned tabs. But that doesn’t replace tab stacking. Grouping tabs and moving them around as one (even to a seperate window) would be so useful and save a lot of space.

          • iwod

            I dont see how Tab Stacking and Pin Tab has any relation. As a matter of fact I have stopped using Pin Tab long time ago. Those pinned tab are likely things you check constantly like RSS Reader, Facebook, Twitter, Gmail. All of them now lives as Apps on my Phone or Separate Apps on Task Bar.

            It doesn’t need to be Tab Stacking or Tab Overflow. We need a way to sort out people who have lots of tabs to go through.

  • inDigazzZ
    • Ralf Brinkmann

      I don’t understand what you want to say.

      • Sidney Guioy

        looks like the text got hidden ( weird offset, so you can see full text anymore )

  • Ralf Brinkmann

    Oh, you changed the order of the buttons in the download page. So I can jump to “Clear downloads” with a simple TAB now. Good! I like it.

  • Bandes

    starts crashing every start now
    “well done”

    • Marcin Mitek

      Have you upgraded your previous installation by yourself (by downloading net installer and pointing it to upgrade previous installation) or was it autoupdated automatically?

      • Bandes

        Yesterday it updated itself to 43.0.2431.0 and then autoupdate started crashing today when i was starting Opera Developer.
        I turned off all the scheduled updates in Task Scheduler. Now it doesn’t crash anymore when i start it. Anyway i don’t need background updates. It can hog the cpu just when i am doing something important. I have the About tab pinned so when i open Opera i check that tab and then it checks anyway if there is a new version.

      • led9ru

        After offline install Opera it start yourself, I close Opera. And go to task manager to close the damn opera_autoupdate.exe! It not close yourself!! NEVER!

        Is this normal behavior of the program? If the user chooses to close your browser, you should be clear that the user wants to close all parts of your browser.

        Is not bad form to programming, when user must run the program manager to close your program, because it does not close itself?

    • Chawoobie

      What anti-virus/security program are you running? I had same problem with last update, as well as this one. Turned out Norton Security was detecting something in the update as a virus and closing it. I had to submit report to Norton to get them to change it, but it only applied for that specific update. They indicated that any future updates would likely have the same problem.

      Wonder if Opera is doing something different in the build to cause the crash.

      • Bandes

        NONE. Myself. Process Explorer. Autoruns, msconfig 🙂
        Turned off scheduled updates in Task Scheduler and problem stopped appearing.

    • NoName

      Opera crashed the first time it booted up after this update. (I saw the main window open, but crashed while the tabs in my session was appearing in the UI)

      Don’t know it this is realated.
      It has not crashed since.

  • Junaid Ahmed

    Can anyone tell me the difference between this feature and already existing “Predict network actions to improve page load performance” feature?

    • Daniel Bratell

      Already before prerender we used to look up information in DNS and maybe even establish a server connection in anticipation of a link click (for instance). This saved a bit of time. Now we (sometimes) render the whole page in the background as well.

      From a technical perspective prerendering is much more advanced and have the potential to speed up page loads more. I am really looking forward to hearing about people’s own experiences here, though the effect will probably mostly just be magically quick page loads.

  • epigastrium

    there’s – unchanged – the keyring request (pop-up), starting up to date Opera 43-dev in/under Linux Xubuntu 14.04, every session:

    • epigastrium

      same in ubuntu GNOME 14.04 lts!

  • SiMcarD

    Old “bug” (?): Facebook video profiles doesn’t play automatically.

  • Matheus Bombonato

    I’m having some weird behavior on the last 2 dev builds. Sometimes, my tabs doesn’t fill the whole window. It happens randomly on websites or internal pages (speeddial, bookmarks…).
    Windows 10/64bits

    • Rafał Chłodnicki

      Should be fixed in next build.

  • Luis A. Rosario

    On the last 2 dev builds, file assoc such GIF, MHTML doesn’t works; also tried to set it on “set your default programs” and issues persist.

    • Luis A. Rosario


      • Leonardo Gomes

        This is not a forum. 🙂


    What this two icons in all fullscreen videos?

    • Leonardo Gomes

      As already answered in your previous comment, this is not something from Opera.

      Probably an extension adding them?

      • Marc

        Looks like Nvidia Shadowplay overlay.

        • SiMcarD

          I confirm.


        It shows only in Opera and even in incognito mode.

        • Leonardo Gomes

          Not here. I never saw such buttons before have seen your image.

  • hakan güven

    operayı seviyorum. fakat bazı konularda daha fazla rakipleri için ön plana çıkmalı. rakipler çok yaygın ve güçlü. opera için daha iyi deslekler gerekli. vr konusunda henüz opera başarılı değil.

  • Marko Koivuniemi

    Has anyone noticed problems with this build in Facebook? Sometimes I cannot comment fb-statuses and various other things. Tried with interna ad-block disabled and enabled. And I have not any extensions installed.

    • aBallerDotCom

      Simple fix, stop using Facebook.

      • Harry

        Stop using Facebook?

        Heresy! The man is a witch. Prepare the stake and kindling.

      • Marko Koivuniemi

        We have Sherlock Holmes himself here.

  • aBallerDotCom


    tried that link and it does not work.

    This link works great though

  • mb

    Anyone having excessive crashes lately? 2x Win 10 x64 machines

    • Leonardo Gomes

      How those crashes usually happens?

  • Herr Pietrus

    How this function compares with the actually existing feature called “Predict network actions to improve page load performance”

  • L33t4opera

    The first Opera developer 44.0.2440.0 😉
    (so far for Windows only)

  • passie

    when maximizing a youtube movie on the imac you will get a white bar. second when resizing a window from full to half width and resize back to full the page is still half sized.

  • Luis A. Rosario

    I wonder why Opera Beta has infiltrated in Opera Developer’s thread?

    • Leonardo Gomes

      What are you talking about?

  • Le

    VPN, UK option when?

  • Doktordan Haberler

    operayı seviyorum. fakat bazı konularda daha fazla rakipleri için ön plana çıkmalı. rakipler çok yaygın ve güçlü.
    Erhan Yavuz

    • Leonardo Gomes

      The video seems to use some unsupported codec/format so it fallback to Flash player. Do you have Flash running?

  • bratpit


    1. Opera_autoupdate segfaults non stop.

    [11740.399321] IPCThread[26795]: segfault at 0 ip 0000000000466bd0 sp 0000031819dd5bf8 error 4 in opera_autoupdate[400000+3c6000]

    2. Autocomplete names in search field /Google, Duck../ stop working

    3. Download this file /archive tar.gz/:

    change it’s real size and some packagers can not open it.

  • Angry Penguin

    H264 and MSE & H264 not working on Opera 43 developer on Linux Ubuntu 16.10 x64. On system I have installed ffmpeg-codecs-extra 57

  • Fastest browser. I Love you Opera .!