Yeah, I had that battle one too many times. "how could the FBI possibly check thousands of emails for duplicates in a mere 48 hours! Miscarriage of justice! Turribl! Turribl!"
here's the thing: Comey came forward because they had "become aware" of emails on Anthony Weiner's computer and they "did not know" if there was anything new so they were "reopening the investigation" under a "preponderance of caution."
But I'm not the FBI and if you gave me two databases with tens of thousands of emails each, I could tell you which ones were new inside of ten minutes. I do it every month. So on the one hand we've got "oh god she violated national security hundreds or thousands of times!" when in fact none of the emails under discussion were classified at the time anyone was handling them and on the other hand we've got "we have reasons to believe that this laptop we got was a backup target for another device we already have and I'll bet if we look we'll find some backups."
Dude is the director of the FBI. There's every reason to believe he's slightly better at technology than your aunt Verna. The fact that he's acting like he isn't is partisan hackery, not innocent incompetence.