It slows down the browsing, the browser consumes 99% CPU for like 2 seconds after a page is loaded. And editing a page with some mathjax expressions is hell slow, probably because of preview. Why can't you do the same on server side, at least partially? There is a golden rule: don't do on client's side what you can do on server's side with the same result. And don't do something in javascript that you can do without.

  • $\begingroup$ What browser are you using? $\endgroup$ Mar 5, 2013 at 19:37
  • $\begingroup$ Firefox 3 and a laptop with 1,4 GHz CPU. Don't tell about buying a new. $\endgroup$ Mar 5, 2013 at 23:35
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    $\begingroup$ Try a few different browsers. I'm on Chrome and it works fairly quickly. $\endgroup$
    – mikeazo
    Mar 8, 2013 at 1:27
  • $\begingroup$ So, now I use latest Firefox 19 and the site still consumes 99% CPU for a couple of seconds. What do you want to say now? $\endgroup$ Mar 14, 2013 at 20:25
  • $\begingroup$ In case of doubt, block mathjax with something like adblock plus. You’ll lose the nice math rendering, but your CPU will purr like a kitty… and you don’t have to buy a new computer to block a single javascript. ;) $\endgroup$
    – e-sushi
    May 17, 2014 at 2:58

2 Answers 2


Sorry to hear it is not working so well for you.

I don't work for StackExchange and cannot give you an official answer, but I'll share my impression of one reason why you might not want to do this rendering on the server. Doing it on the server side would degrade the quality of some site features. For instance, when users type in an answer (or edit an answer), they wouldn't be able to get real-time feedback seeing how the answer looks. That's an important and useful feature for many users. Breaking that would be most unfortunate.

This site is not optimized for folks with older, slower computers, so yes, if you have an older, slower computer, the site will be slow on questions that use LaTeX equations. That's probably a fact of life at this point. I doubt StackExchange will do anything about it -- nor would I recommend that they change anything, as the current set-up seems to work well enough for the overwhelming majority of the community. It's not reasonable to expect them to make significant changes to support one user, so unless there is an enormous groundswell of support from this community for making such a change, I doubt any such change is likely to happen.

  • $\begingroup$ This "real-time preview" slows down at most. Besides that, i don't know which work and how is done by javascript. The site in general is fast enought - just mathjax is like a turtle. Maybe this community enjoys when a site loads several seconds - i don't! And which computer do you need for mathjax to load fast? How about tablets? They are even weaker. $\endgroup$ Mar 6, 2013 at 12:12
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    $\begingroup$ @SmitJohnth Even an outdated tablet is considerably more powerful than the specs you gave above. It's not possible to please everyone, and you are at the tail of the user curve in terms of hardware capabilities, there is just not much StackExchange can do to help you without impacting user experience for everyone else. Rendering LaTeX takes computational power, that is a fact of life. If changing browsers, etc.. don't work for you, you could consider upgrading. That said, you can always try and turn off JS or otherwise disable Mathjax while editing, of course you'll lose the preview though. $\endgroup$
    – Thomas
    Mar 6, 2013 at 20:55
  • $\begingroup$ @Thomas double-core 1 GHz ARM or whatever frequency tablets have is slower than 1,4 GHz x86. If i would update my hardware, then surely not because of someone's poor software development skills on a site i don't visit very often. And no, this is not a fact of life, there are surely possibilities to make it better, like the possibility making it on the server side i mentioned above. In this case, it can be cached, since changing occures much more seldom than opening pages. $\endgroup$ Mar 7, 2013 at 21:01
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    $\begingroup$ Why are you getting so worked up about this if it's a "site i don't visit very often"? Besides, you should really reconsider your tone when asking for improvements to a service that you neither pay for nor are obliged to use. $\endgroup$
    – us2012
    Mar 19, 2013 at 17:11

Firefox 3 has major security issues, which can be exploited by just visiting an (infected) website. By using software with known security issues, you might be liable for damages caused by attackers using your computer as a relay.

Modern browsers execute JavaScript orders of magnitude faster because they compile it to machine code. And yes, modern browsers do work on your hardware.

  • $\begingroup$ And you think mathjax works in modern browsers significally faster? I vahe to test it, but i doubt that. $\endgroup$ Mar 6, 2013 at 14:42
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    $\begingroup$ @SmitJohnth Yes. Old Firefox versions have a particularly slow JavaScript engine, and MathJax very noticeably brings out that slowness. Get a recent version of Firefox or Chrome. $\endgroup$ Mar 8, 2013 at 14:08

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