How do I improve Freezing Salvo ammunition accumulation?

[Verfolgen]

Hello, I'm looking for advise on a build. Just wondering about the Bow Skill named Freezing salvo which accumulates a missile every 1.05 seconds at level 1 up to 0.8 seconds at level 20 and can be leveled past 20 from bonuses, how do I improve the accumulation time so I could fire more missiles aside from skill level increase?

Additional projectile from Endless munition skill (+1) from Deadeye ascendancy and Dualstring Bow (+1), the unique bow Death's Harp Dualstring Bow (+3) can increase the projectile count. Aside from these, are there other ways to boost the skill?

[Drake]

Scattershot support should also work for +2

[Verfolgen]

Thanks for that, I forgot about Scattershot.
Which support gems also has great synergy with Frozen Salvo?