Hair will take 10 sec. preparig before I can see the first rendering with map based colored ... strands? in viewport. 100.000 Hairs with 3 segments, krinkeled and knitted cones (don't know the exact english words).
That is fast to my machine for hair, but slow compared to your pure scattering object. scattering based on a b/w map, cones with 3 hight segment and 6 arround - but in white ^^
Now, compared to bepeg's method with InstanceColor node plus texture effector and based on particles scattering, this takes 30 secods and more to prepare and start rendering. But it is hard to compare, since I scatter the cones via b/w-map in scatter-object scale slot - so I have to use about 5 times more clones and more toget a similar effect. Probably thats the problem? May I send you the file if you have time for an eye on it?
And also viewport is very slow with this method. rendering itself is normally-fast.
