Simply Open Pool Window and highlight the wav file.
Click the Musical Mode box so an X appears.
Underneath the Algorithm heading click on the name of whatever algorithm is showing and then you will see a long list of different algorithms which work best depending on the source material. My tip for you is to first try Elastique Pro - Time which should give you the tightest rhythm BUT if you’re timeshifting by a small amount Elastique Pro - Pitch may be your better option because it will retain the pitch of the hi-hats better so they sound more realistic. It’s best to experiment with the Pro algorithms! Also take note of how all the other Pro algorithms affect different sound sources!
Anyways, I hope this resolves your issue?