Deleting hidden file has caused me problems

At least I believe that to be so . My Mac has been rather slow so I set about deleting apps I didnt use plus associated files using App Cleaner. Everything seemed to be much better but then I decided i would find any hidden files by using the following process but i dont think i got it quite right..http://computers.tutsplus.com/tutorials/quick-tip-revealing-hidden-files-in-os-x --mac-48663 In any case I deleted the files and now my computer is very much slower than it was, sometimes requiring 3 or 4 reloads to load a page .I then tried to use Tinker Tool maintenance "Clear Memory Cache " but got the following mesage- "A required component of OS X is missing in your system installation Please verify that the UNIX program discoveryutil is present at its standard path '/usr/sbin/discoveryutil'. Note: The problem was detected while working with the file system object “/usr/sbin/discoveryutil”. That means absolutely nothing to me so I was wondering if someone could advise me as i am at my wits end. Thanks