Winows 10 not using my hdd full potential

[monokiller]

So i runned a benchmark on my hdd the reading speed is 134.9 and write 135.4 MB/s, but i am experiencing slowdowns while using windows, slow boot time, problem with rendering in games which appears only on windows 10. Always when i do something hdd heavy like installing a game for example, the maximum speed i see is around 30MB/s. Is there any way to fix this ? Also i forgot to mention my hdd is Hitachi HDS721050CLA360 500GB.

 

[kanewolf]

How full is the disk? How fragmented? Those are the things that can hurt HDD speeds.

 

[monokiller]

I have about 390GB free, and i defragment the hdd frequently that's not the problem.