We are running Magento EE 1.11 with memcache. 2GB per memcahce server, 4GB total. We have about 240k products.

* Available ram: 6GB
* Cores: 16
* Threads: 32

Here is the deal, more new products are added and changes to products occur on a daily basis and of course each time a new product is added/modified in the back-end the cache becomes invalidated, specifically the 'Full Page Cache'.

When Magentos Auto Cache Generation is enabled it takes about 2 days to build up the cache, with 8 threads allocated to the crawler. After 2 days the memcache floats around ~2GB separated between the two ram disks.

The problem is, when products are modified on a daily basis the cache becomes invalidated and as soon as 'Full Page Cache' is refreshed those 2GB of cache are back to square one, 0, and the viscous cycle of Magentos Auto cache starts again. Now, not only is the cache back to 0, but the CPU usage spikes to 90% and the website turns into a 5-10+ seconds waiting game and you can just forget about trying to request a product with 100+ variations, if it's not cached it would take minutes to load the first time, it's ridiculous.

**So, my questions to the community.**

* Is there a way for Magento to automatically "update" the cache if invalidated, without rebuilding the whole cache and starting from 0? I know when the cache is invalidated that Magento knows somethings has changed, but not exactly where in the cache (correct me if I'm wrong). Are there modules/configurations out there to bypass rebuilding the whole cache?

On the side note, we are using Tiny Bricks LightSpeed module.

* Can Magentos Automatic Cache Generation be time controlled with a cronjob? Say, to start crawling at 10pm - 6am.
* What would be the best way to approach this situation?, As you understand rebuilding a cache that's in gigabytes everyday is just not acceptable.