problem to display pdf throw the browser

Hello,

We've got problem when we try to display relatively big file in pdf (for instance 1,7Mo)

The browser/pdf displayer (acrobat) halt to load after annoncing 1/3 loaded

If we use the simple "right-click option/dowload this file", it works fine anf fast.

Why ?

Thanks for your help.

We use : Apache 2.0.58 + Cocoon 2.1.9