Running parallel tasks in Ansible is not a problem. Ansible or in fact any kind of configuration management tool was meant for this. They are suppossed to be provisioning multiple host systems simultaneously and hence parallel execution of jobs is one of their strengths. 
You can achieve the parallel execution of tasks on Ansible by just using a keyword called 'serial' in the following manner:
- name: test play
  hosts: webservers
  serial: 2
  gather_facts: False
  tasks:
  - name: task one
    command: hostname
  - name: task two
    command: hostname