I arrived to this thread after facing a lot of problems with this opcache.
Initially when I installed PHP-FPM 5.5 on my server, the wordpress admin panel was very fast (I didn't know it was the work of opcache) and I was very happy.
But I was facing strange problems whenever I saved settings or posts. I had to submit it twice for the changes to be saved. First I thought it was due to APCu (yes as dfumagalli rightfully said APC is available via dotdeb repository. I installed it using "apt-get install php5-apcu") and checked the apc.stat setting (if this is set to 0 similar problems will occur) but it was set to 1 only.
Then I thought it was something related to nginx but that too wasn't the case. Then after checking "modules loaded" by PHP I found it was due to opcache.
So I disabled it only in the admin pages by adding the following code to "functions.php"
if(is_admin()):
ini_set("opcache.enable","0");
endif;That solved the Wordpress problem but I also had phpMyadmin installed. It started halting abruptly during delete queries.
I sometimes had to double check through the mysql command-line if data was in fact deleted. So now I have commented out opcache.so module from loading and everything is back to normal.
After all W3TC creates static pages so I don't need opcache :)