Unfortunately we have not had a happy experience so far.
The product appears to be extremely flaky and unstable (at least that has been our experience).
These are the problems we have encountered:
a) In the free version of Smush, the smushing never appears to complete and you have to keep refreshing the page to see the results (it must be working in the background but unless you refresh you could be waiting until the cows come home.
b) It is now doing exactly the same in Pro
Refreshing or cancelling is the only way to stop it from reporting 0% https://www.screencast.com/t/TjG9uLnHVza
But I estimate I would have do do that maybe 50 times which I am not prepared to do.
I think Hummingbird may have been hit by buckshot and is badly wounded.
Well, rather, the website itself was hit by buckshot!!! Or more like a wrecking ball really.
So there we were, gloating in the fact that we had come down from 5-8 seconds to 1.8 to 2.3 seconds after running Hummingbird but then fortuitously checked the frontend to ensure everything looked fine.
It was at that point we realised that the only reason we were getting such good results was because the site had been trashed and there was nothing for the server to server!! - only two out of six menu items worked and major elements on the front page no longer existed.
We restored the site from a backed up version.
We would not take the risk of repeating the exercise.
So we have decided to use WPMU Dev simply for optimizing images (an hour later this is what appears (ie 0% progress):
We also found the UX in general provided insufficient information as to what our expectations should be as the performance optimization process progressed - it was very very slow and regular refreshing seemed to be the only way to get it to complete the task.
And if the optimization process is likely to be doing things that will completely break the site would not warnings be given?
In any event the result was a shambles and by right we should just uninstall it and cancel our subscription.
However I thought that we should at least obtain your feedback on our experience. Maybe there are contributing factors that can be dealt with?
Looking forward to hearing back from you.
Thanks and regards,