[OS X TeX] Slow PNG typestting

[BELLAICHE André]

I have two macs and something strange happens:

On the 1st one, with Mac OS 10.6.8 and pdftex Version 3.1415926-1.40.11 (TeX LIve 2010), PNG image files are typeset like flashes of lightning.

On the 2nd one, with Mac OS 10.8.5 and pdftex Version 3.1415926-2.5-1.40.14 (TeX Live 2013), PNG image files are painfully typeset one by one, and the global times of typesetting is multiplied by 10 or 20. 

The file is exactly the same on both computers, and package used are basically

\usepackage[update]{epstopdf}
\usepackage{microtype}

Does anybody understand what is happening and know what to do?

André Bellaïche