Why is Smush Pro stopping all the time ?

Hi

Recently, I bought and installed Smush Pro with no problems.

After running it for some hours, I found that it keeps stopping.

Then I have to reload and start it again, where it continues from the point it stalled.

After some weeks, this "starting and stopping" has brought me no further than 49% of my images, so it's very disappointing to me.

Can you please help me make the plugin finish the job once and for all?