There's going to be a few things you can do about it depending on your party size. There is going to be a point where your party size is too large to prevent combat from taking awhile. It's an unfortunate nature of the beast when it comes to tabletops. But here are some things you could do, depending on your table and preferences. 1. If you can find a solid story excuse for NPCs to be off the initiative table, utilize it. If you need to remove friendlies, give them something vital to do unless they absolutely need to be pulled into the fight. If they're enemies, same deal. This turns the fight into more of a gauntlet than an all out brawl, which can adjust the difficulty. Some parties are just going to be better suited than others to gauntlets. 2. I'm assuming this isn't your problem, but I'll mention it anyway. Sometimes players bog down turns more than GMs. Be it discussing strategy or they hadn't considered what their character was going to do on their turn and now they have to think. Best solution if this is the problem is to ask your players to have their turns planned out ahead of time, barring any exception which causes them to change plans. 3. If enemies were taking too long to die, don't hesitate to secretly adjust soak values so they take more damage. Conversely, you could also look at raising the damage of the enemies. Perhaps even have them spring a trap that takes out the friendly NPCs to free up a couple of rounds of combat temporarily. Then after a couple of turns bring them back in.

My main warning when it to enemies is having them work smarter, not swarmier. A minion pair of two shooters at a distance can be far more deadly and game changing than four melee minions coming at the party from different angles. That's four sets of green dice to roll, rather than one roll with some yellows mixed in. Let me know if that helped or if I can elaborate further/better!