Using Smush/SmushPro on site with usage overload to Optimize

Hi, I went to use Smush and then Smush Pro because my site has over 4500 images; it is really slow and causing me problems. I deleted a bunch of plug-ins and am trying to optimize it. When I installed WPMU Dashboard plugin and Smush Pro, it was too much for the site to handle and I had to uninstall them (it would not let me utilize them and would go to Page Not Found).

I am now doing the images via regular Smush but it is taking a very long time. I gather I cannot use SmushPro without the WPMU Dashboard on the trial. Any other tips for how to make my site not such a nightmare and try out your plugins? Thanks!