You can choose different level of detail for the stats output. See the package documentation for more informations.
Level Output
High More stats available but take longer to compute. Useful for small site.
Medium Default level. More details about the stats.
Minimum Basic main stats are computed.
Low Only one report page about the key stats numbers.

1 Gb logfile Time RAM
Level 3 15 minutes 100 Mb
Level 4 1 hour 1,2 Gb