Had some time today to retest the Turret attack frequency while changing the Skill Speed stat. Since I wanted to see the difference over a longer period than a couple minutes.

2.64 Weapon Delay - 354 SPD
10 Minutes (600 seconds)
186 Hits
2.48 Weapon Delay - 720 SPD
10 Minutes (600 seconds)
186 Hits

Unless the effect is even lower than what SMN pets benefit, I don't think Turret is effected at all by SPD.