Page Cache not working properly

It’s been a while that I can’t use Page Cache in W3 Total Cache anymore. I can’t relate to any specific event, but:

1 – When I try to use it in “Disk: Enhanced” mode the WordPress Admin gets really slow and editing/publishing new posts. Also, after a quick while, as the cache gets bigger, I can’t use the “Empty page cache” button anymore as it will take forever to run and eventually give me a 500 Internal Server Error.

2 – When I try to use it in “Memcached” mode everything seems to work just fine, however caches aren’t cleared when creating new posts or editing them. Not even a manual “Purge cache” will do it.

Any ideas? Thanks.

https://wordpress.org/plugins/w3-total-cache/