Google I/O 2012 – Jank Busters: Building Performant Web Apps

Building high-performance web apps is hard! When animations hitch, mouse hover effects lag, or page scrolls stutter, we call it jank. This talk is about hunting jank down and exterminating it.

Sources of jank in web apps include garbage collector runs, long image decodes, heavy paint times for DOM elements, JavaScript-heavy input handlers, unexpected WebKit layer invalidations, and more — all getting in the way of the 60FPS every modern app developer should aim for. In this talk we’ll go through a few techniques to ensure your web app has smooth animations, transitions, and scrolling. We’ll cover ways to use Chrome’s Developer Tools to root out jank, as well as more advanced Chrome graphics profiling tools the intrepid can use to dig into what’s going on behind the scenes. We’ll even peek gingerly under the covers of WebKit to explain why that pesky hitch occurs in the first place.

Useful tips & links for learning English outside the classroom

I’ll let you on to a little secret: if you think that you will learn to speak English like a native speaker just by coming to class twice a week, you’re wrong!

It’s like practicing for your driver’s test, it’s not enough to just pass the test, you have to actually drive everyday in the traffic to be able to say that you can drive. Otherwise you’ll just forget and you won’t be able to drive anymore after a few weeks or months.
The same is true about language learning. You have to practice and practice, and did I mention practice?

“But teacher, I don’t have time to study at home!,” I often hear as an excuse.
I don’t want to sound harsh, but I think you are wasting your money and your time paying for lessons if you’re not committed to your goal. Don’t tell me you don’t have 10 minutes everyday to:

  • listen to a short news clip from the BBC
  • read a short article and look up words you don’t understand
  • listen to a song in English and see how many words or sentences you understand or recognize
  • write a short email to your teacher, and ask him to correct it or annotate the mistakes so that you may do the corrections yourself the next day
  • chatting to other English students on a social network IN ENGLISH
  • speaking to other English students with voice over MSN or SKYPE
  • even better, make friends with native speakers on a social network and chat with them! Be careful though, you never know who you can meet online…don’t give out your address or credit card number 😉

Useful links

Ingles online, a Brazilian site/

The American’s guide to speaking British English

About.com Huge resource for learning English

Correspond in English

Huge list of links for learning English

BBC Learning English

Read books online by daily email

Listen to free audio books

Well that’s it for today!
No more excuses for not practicing your English at least 10 minutes a day.
You’ll notice your progress and so will your teacher

Students’ expectations for the course

As you know, I asked you to write a small paragraph about your expectations for the course this semester
Here are the first two I received, please keep them coming!

I have high expectations for this semester. The kind of activities I enjoy and would like to do more of include games,  video & song activities.

For myself I want to improve my fluency and to do the web lessons


I want to enrich my vocabulary this semester. I will participate more actively in activities involving speaking skills, because I want to improve my conversation.

I would like more video & song activities as well as games this semester.


Ok, this time I corrected your texts, but next time I will post it as is, then we can do a group correction in class.

Projects kick-off

Ok, so this semester there will be two group projects.

The groups have been formed :

Group 1 will do a presentation about the cities of Recife and Venice, discussing similarities and differences between the two.


  • Joyce
  • Thalita
  • Rebecca
  • Patricia

Group 2 will give a presentation about sports, notably the different styles of sports played by the American and the British.


  • Bruno
  • Silvia
  • Irene
  • Flavia

May I remind you to start doing your research, and I will be expecting a rough plan, roles and ideas for making the presentation interesting for the first class in March



Hello everybody,

I don’t have any definite plans as to what this blog will contain, or what purpose it will serve. Let’s treat it as an experiment – and see what we can get out of it.

I think one idea is that we can use it as a journal, so that we may follow the evolution of the activities we do during the semester and also talk about the projects.

Another goal would be to encourage students to write in English, you could use the blog to write about anything that crosses your mind or captures your interest at a particular time, and share it with the others.

I won’t post your grades here, don’ t worry!

See you in class!