I have been using G.I.M.P SINCE 1999 (version 0.99b) but have only had a Macbook since late 2012.

A few months back I maxed out the ram to 16Gig but noticed that G.I.M.P was lagging when calling up commands and really struggling while working on a book cover (sys report showed only half the ram was in use!) its taken me ages but last week I found the issue.

When I upped the ram, I forgot to change a setting in G.I.M.P, this setting is “Tile Size”. Once I changed this to use 8 gig, G.I.M.P started working perfectly. If anyone is finding this issue, I hope this post helps you out!