[Hummingbird Pro] Crashed site

After installing hummingbird and running a Asset Optimization activation the site crashed and slowed down repeatedly over a 2 hour period while the Asset optimization was checking files. This check never made it past 7%. Seemed to hang there for a long time. The site was unusable and stalled even after stopping the asset optimization check. I disabled Smush and Hummingbird and the site worked ok again. We ran the same plugins on a dev site, Hosted with you, and everything worked fine. I think It might be a server issue, but not sure where to start.

Can yon suggest what may be going on here?Thanks!