Garbage collection in options.w3tc_minify

Hello,

I am having an issue with the w3tc_minify option in table wp_options growing indefinitely without getting purged.

Short version:
after manually deleting the w3tc_minify option from the database, a WooCommerce product page on my site that used to be generated in 114 msec is now served in 98 msec (full load test using the ab tool).

Long version:
my site runs with ~25 minified files in cache/minify. After running the site for more than 1 year, I noticed that option w3tc_minify grew to 145 KB. It contained a list of 320 minified files along the the path of the originating files. Many of the files referenced in there were from older plugin that are not in use anymore, even plugins activated months ago for just a few days. Apparently the various manual purge buttons are not purging this. The option is cached by APC as object cache, still it’s deserialized on each pageview and it probably increases w3tc processing time.

After manually deleting the option from the wp_options table and purging APC, it is recreated within a few pageviews and it reaches 6 KB only.
The average time for generating a Wocommerce product page decresed from 114 msec down to 98 msec (-14%).

Is there a mechanism for purging the content of w3tc_minify ? Is that not working just on my system maybe ?
Otherwise I would suggest to fully delete that option once a month, so that it does not accumulate garbage over time and it keeps the site running faster. Or at least delete every month the entries containing non-existing files on the filesystem, although this would be a partial cleanup (I had for example entries related to the old hostname the site was running on).

Regards,
Nicola