[WIN7] Very strange "slight delay" behavior on start-u

I don't know if it's one of the new Windows updates, my new SSD, newer updated AntiVir antivirus or? For example, if I'm to rename a folder/file, its NOT showing the folder/file "new" name instantly (but its actually done) cause if I'm to close the folder and re open it again, it will show the folder/file "new" name. Same thing also in recycle bin, all items deleted, but still showing, close and re open the recycle bin folder would show empty recycle bin. This strange "slight delay" behavior ONLY happens on the 1st instance of every start-ups/reboots, and after about 1 min of use, everything is instant/no whatsoever delay. All my hard drives, including the SSD passed SMART test as well as Western Digital/Samsung own tests. What could it be? Thanks.