Don't just look for Speed Secondaries, Try to get Potency Secondaries. You can get +10% potency in secondary I think. I would consider +%5 potency as high end.
https://cdn.discordapp.com/attachments/188181869832044545/320930583637393409/IMG_0133.PNG
https://cdn.discordapp.com/attachments/188181869832044545/320930456227020801/IMG_0134.PNG