On my last website, the text is perfect naturally on chrome and firefox without touching font-smoothing or anything else.   
But on Mac / Safari 7 the text appears well then turns immediately thinner (too much thinner / not nice to read).
![enter image description here][1]
![enter image description here][2]

After doing some research [cf http://www.usabilitypost.com/2012/11/05/stop-fixing-font-smoothing/]  
and some tests playing with 

    -webkit-font-smoothing    

It looks like Safari display the text first with :

    -webkit-font-smoothing: subpixel-antialiased;

Then just after you got the flickering effect, when it is turning font to :

    -webkit-font-smoothing: antialiased;



So it seems to me that I had no choice but to force 

    -webkit-font-smoothing: subpixel-antialiased;

to make my website consistent on all browsers.  
I am using font-face Avenir Std Roman.

Some explanations to that Safari problem ?
Any better solutions ?
Could my font be part of the problem ?

Thanks.


  [1]: http://i.stack.imgur.com/RLaop.png
  [2]: http://i.stack.imgur.com/de7le.png

All Font Smoothing Solutions on Gang of Coders

Total of 1 Font Smoothing Solutions

Font weight turns lighter on Mac/Safari