So here is what i found so far.
Importing assets: no crash recorded so far.
Building a level from default static meshes: no problem detected
Lightning: yep it does crash a lot randomly.
Particle editor: yes crashes randomly
renderer: needs to be really rewriten: not only defered , but forward as well. weird shadow artefacts , i can see shadow underground :0) funny.
So main areas causing problems are Lightning , particles. I have not tested the material editor much yet. will do today