Advice on DMing

Hello

Recently ive been having problems in my sessions. When certain player is around everything is rushed. Usually, session goes like

New day, what have you been doing (its usually just to introduce what were the characters doing)

Then, i introduce to one or more of them an event. In this scenario, as the mage went to to look around he noticed a really bad scent. Like, rotting. He then went to his allies to call for it.

Then, the group goes to that event. Asks the villagers around, and investigate. After 1 or 2 travel dices, they get to the location.

The notorius monster (the ones who cause the problem) appears and conflict scene.

They defeat it and goes back to the village to bring the news.

They prepare and discuss the main target.

Thing is, usually session last 3h, but when that player is around, group rushes the content planned for the session and im out for interesting ideas to keep it going, making sessions last 2h.

Have to say that hes a min maxer dps and he uses every element so he hits weakness, he has cheapshot too, power shoot heroic, and the Zero who has +20 damage if atk with single weapon. So he constantly does 50-60 damage per turn, and 100 when that zero.

How can i make conflicts around that player? Limmiting vulnerabilities doesnt really seem the way because other players have reduced options to do damage, and this last monster put them on the edge due Devastation+ Minor hazzard damage at end of round (which because of their decission making, made a player surrender cuz defeated)(weakest hp player had 65 hp and that combibation did 55hp at much)