I was checking the stats today and i noticed that the some graphs have stats since i 2 years ago.
Isn´t possible to delete stats for 6 months ago , if users agree of course.

i don't see how the length of the history kept relates to the speed of the stats (your topic title)

I'm thinking that his idea is to only show the last 6 months (or whatever) for each graph, in that displaying less data will place less of a load on the database when it goes to build those graphs in the first place.

I don't know, however, if this would yield a realistic decrease in system resources used. Don't know how the back-end is set up to serve those graphs.

potentially it could, however willy seems to be a competant coder and i'm sure things are cached or a script/process writes data to a static file which is then served rather then being generated on demand

as for the database, load is only caused when something is done, like adding lots of new data to it (and the size of the updates and the DB itself are growing, therefore load increases exponentially) and with all the web requests the single server was unable to handle everything, so the DB and web front are being split

in short from various things i've read i don't think it would have any noticable impact in the load at all, however i could be wrong, only willy can give a definate answer