If reading 3 GB takes 5 minutes, you only get 10 MB/s. My guess is your hdd is fragmented too much.
Thanks. Just found that defragsvc was disabled unexpectedly.
(haha, someone encountered the same problem: [defragment-drives-dfrgui-exe-wont-start-after-1703-update from superuser - URL was automatically removed!? ] )
I've defraged my HDD, hope this will help.