I have a .blend file that I have appended about 30+ objects from other .blend files into. in 2.6 this renders fine in GLSL mode with textures turned on but in 2.7 it slows to a crawl (when rotating the scene around in real-time). So I tried a fresh scene and started appending objects, it rendered (in real-time) just fine until I appended the fourth object. so I started to remove the abundance of extra materials on some of the objects and it went back to normal. so it seems to have something to do with the overall amount of materials attached to an object.