Disk usage always 100%

my HDD is always at 100% usage, there are some examples in the video. i dont know when it started but since today GTA V started stuttering insanely and the sound was crackling.it makes the game absolutely unplayable. My HDD: Western Digital Blue its a 7200 RPM drive and should be able to handle 150MB/s easily but it already tops 100% when programs arent using more than 0,2MB/s i have tried every option i found online: disabling superfetch and windows search, trying a different antivirus, changing the page file size and so on. could my HDD be broken? please if you know how to fix this let me know in the comments.