Disk usage at 100% during startup

Every time I start my computer, I have to wait 15 – 20 minutes just for it to actually be usable because disk usage is stuck at 100% and causing high lag. I have no ideo why, and I tried a few solutions like disabling windows search. The running processes also dont add up to 100%, sometimes the highest running usage is only around 16% but it still shows a total of 100%. Usually system is the highest one though. If it helps, im on windows 10 and have an HDD disk, computer was made in 2015