Sorry, it's called "Installation or Upgrade.txt".
The tutorial about each option is written on the options themselves, however I will ask our documentation writer to prioritise writing a full manual for vB Optimise
If page speed is slower after using Filecache, then your server's harddrives may be too slow so that bottleneck shifts from MySQL (waiting for queries to load) to the HDD (waiting for the drive to load the cache files).
If you do not have the possibility to request your host to install and configure an opcode cacher like APC or XCache (I recommend APC since it's easier to install) then unfortunately vB Optimise cannot help you
Fillip