Pc block with 2 .eaf file open

I’m using Elan 5.4 version for Ubuntu 16.4. When I work with .eaf file with numerous parent and children tiers, or open two .eaf file simultaneously, ubuntu block all other activities after a slowdown. I can’t move the mouse and I have to turn off the computer.
How I can solve it?

It sounds a bit like ELAN is consuming all the CPU time. Did you already check CPU and Memory usage when the computer starts slowing down?
Can you link the problem to a particular activity in ELAN? Are there meaningful (maybe often repeated) error messages in the ELAN log (View->View Log…)?