No idea what are you talking about here people, I’m running more than a hundred of projects with W3TC now, each of them have many different plugin combinations, different wordpress and plugin versions. So far I can testify that Contact Form 7, SI Captcha Anti Spam and Google Anlytics for WordPress do not cause any kinds of problems running together with W3TC. And they never did to my knowledge and from my personal experience, therefore your problems are most probably caused my something else.