In administration panel go to Configuration => Configure modules
Select FastCache module
Your IP number is automatically detected.
FastCache strength determines how often the pages are being optimized (an average of how many page views are needed in order to optimize the page automatically).
For a very large quantity of products (over 5000 products) you can reduce the strength (the system automatically proposes the default and optimal setting) - the often viewed products will be shown faster in relation to the rarely viewed products. It will allow to limit the cache size and keep the high level of optimization.
Determine when to re-generate the FastCache.
Check out how to clear cache.