"...Islam is always said to be religion of peace...yet it so blatantly allows, accepts and is comfortable with death/murder...."

If you need to maintain peace then you may need to reign in miscreants and they need to be punished as per their crime.

According to you :

what should be the punishment for raping a women ??
What should be the punishment of a terrorist or a murderer??

Even death penalty exists as per the laws of most of the countries in the world and most people agree that this is justifiable for heinous crimes. Europe is also having laws where denyign holocaust is a crime.

Hence I dont know why people are having so much problem when Islam is asking for death penalty for extreme blasphemers.

Also as fatima rightly pointed out and gave examples where even big crimes did not result in death penalty.