While the framerate has improved for 4.7 in regards to large amounts of foliage, when a user places a substantial amount of foliage into level and it has at least 3 different foliage meshes, FPS drops dramatically.
Internal reproduction saw a drop from 96 FPS to 28 within moments along with long pauses between input and foliage placement.
1. Open Editor (any project with starter content)
2. Create a 63x63 landscape
3. Add 3 different static meshes to foliage mode
4. press ~
5. Type "Stat FPS">Enter
6. Create very large brush and cover landscape with the 3 meshes.
Head over to the existingAnswerHub thread and let us know what's up.