I get the following sub-point in a report from gtmetrix in respect to my google page speed.
http://www.masjids.co.za/wp-content/plugins/wp-dtree-30/dtree-img/empty.gif (Dimensions: 18 x 18) (931 uses)
http://www.masjids.co.za/wp-content/plugins/wp-dtree-30/dtree-img/nolines_plus.gif (Dimensions: 18 x 18) (12 uses)
I assume it needs to be changed, in wp-dtree-30/wp-dtree.min.js but please advise where and how or what I can try.
Please help. I could test it for you as well and could go into next release.