Hi Damien, OK your advice was the good one :-)
I found that plugin, which force a module in a module position to be loaded through ajax.
I tried it for my Banner module, and it works with Speedcache activated. Now my module dispatch banners randomoly on each page loaded or reloaded...
That's perfetc !
Actually developper say :
Not all modules can be loaded using such a plugin, as some modules may use JS which tries to use DOM which doesn't exists at the Ajax request. Such modules will not work with the plugin. Most modules still work perfect.
For who are interested :
URL
Banner module with Ajax Module Loader URL of the plugin :
Ajax Module Loader