It says a high priority is to compress the .js files - is this something I can do easily myself (is there a setting in xf?).
It also says a number of files can be cached in the browser, as there is currently no expiry set on them. This includes some advertiser graphics and all the header, footer and node graphics. I agree these don't change often, so could be cached. Again, how is this set (I am on shared hosting so would guess this is done either in Xenforo settings, or .htaccess).