Need clarifying first.

Will definitely edit this review’s star rating, but my question is that before i run this plugin is that would you recommend doing a backup (other than pics?) i dont care about the original png’s since i did all the pics myself, but afraid that it sounds too good to be true (no offense intended) im hoping it is. but i used another plugin (jetpack boost) followed all the steps and just made my website slower.. Grade F in GT Metrics.

Any help will be greatly appreciated.