Client Cache deactivated after plugin activation

[gessler]

Hi, I got a problem with some contact forms in general, these four create a session header(token)
GetSimple Contact
Simple C(ontact)
Contact Form
p01-contact.
After activating one of these (tested each one after another) I got this when testing the HTTP Header:
Expires: Thu, 19 Nov 1981 08:52:00 GMT Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0 Pragma: no-cache
No client cache at all at the entire website,
Is this really the expected behavior? Another stupid queston, is there a way to turn on off a plugin on page or template base?
Thanks to anyone in advance