The crashing is most likely like you said too many particles. Having >10 instances of blood literally in the camera is not good, so a weaker PC could crash because of that, so I guess I'll tweak how shotgun impact effects work.
For the jump spots, I am not sure how to treat them: like bugs or like features :D. But I'll probably not change the jump spots, I'd rather focus on making a new map than playtesting to death the first one.