I have a Python script that colors a mesh with 544458 vertices according to the Z of its vertices.
The first time I execute the script in Rhino 6 Beta it says:
Time to color mesh = 76.2056427002 sec
which I thought (before checking Rhino 5) is not too bad for a half-million plus mesh.
Then I found out that if I repeat the same exact script with no changes, it can say:
Time to color mesh = 980.461730957
Can you imagine what it is like to wait over 16 minutes for something that really only takes 16 sec more than 1 minute? But wait it gets worse. If you do this in Rhino 5 you only have to wait 29 sec. See below.
If your expectations were set by Rhino 5:
Typical Rhino 5 times (mostly reproducible, at least within 1.5X)
544458 vertices in mesh.
Time to import .obj file = 12.5874710083
Time to color mesh = 29.3717498779 sec
Then you are going to want to jump out the window when you see the Rhino 6 Beta result:
The best Rhino 6 Beta Times:
544458 vertices in mesh.
Time to import .obj file = 11.9335174561
Time to color mesh = 980.461730957 sec (can be as small as 76 sec, just to drive you crazy)
This slow down and variability I traced to the use of rs.EvaluateSurface. If I do not use this function, the variability can be small. I also suspect other rs. functions are also 10-20X slower.
I extracted a very small subset of the script which illustrates this behavior. You will find it below. Just execute it repeatedly and you should see up to a 4X variation in execution time if your machine is like my machine. Try it in both in Rhino 5 (always faster) and Rhino 6 Beta. Here are the times I got recently:
max_v . Rhino 5… Rhino 6 Beta Slowdown
100 … 0.71 sec …2.87 sec …>>> 4X
200 … 1.42 sec …3.69 sec …>>> 2.5X
300 … 2.14 sec …5.72 sec …>>> 3X
400 … 2.86 sec …23.87 sec …>>>8X
500 … 3.56 sec …34.87 sec …>>>10X
600 … 4.75 sec …47.73 sec …>>>10X
700 … 5.05 sec …63.28 sec …>>>12X but Rhino 6 Beta can do this in 24 sec sometimes.
The Rhino 6 Beta times are not very reproducible. For example, I have seen the max_v = 400 case run in only 8 sec but this is still 3X slower than Rhino 5.
The full code for coloring the mesh has 8X as many calls to rs.EvaluateSurface. Apparently this compounds the slowdown, moving it from 12X to over 20X.
import rhinoscriptsyntax as rs from Rhino.Geometry import Point3d from time import time P3d = Point3d from time import time def problem(srf): time1 = time() max_u = 1070.; max_v = 700. a =  for i in range(int(max_u)): b =  for j in range(int(max_v)): b.append(rs.EvaluateSurface(srf, i, j)) a.append(b) print 'Time to fill matrix = ', time() - time1 return() def makeBase(): pts = [P3d(0,0,942),P3d(0,88,953), P3d(0,175,964), P3d(0,263,973), P3d(0,350,983), P3d(0,438,991), P3d(0,525,986), P3d(0,613,991), P3d(0,700,1000), P3d(220,0,951), P3d(220,88,969), P3d(220,175,976), P3d(220,263,988), P3d(220,350,995), P3d(220,438,1000),P3d(220,525,1000),P3d(220,613,1002),P3d(220,700,999), P3d(267,0,959), P3d(267,88,969), P3d(267,175,977), P3d(267,263,982), P3d(267,350,994), P3d(267,438,998), P3d(267,525,1000),P3d(267,613,1002),P3d(267,700,987), P3d(535,0,934), P3d(535,88,945), P3d(535,175,955), P3d(535,263,963), P3d(535,350,971), P3d(535,438,962), P3d(535,525,967), P3d(535,613,975), P3d(535,700,961), P3d(802,0,890), P3d(802,88,906), P3d(802,175,916), P3d(802,263,922), P3d(802,350,912), P3d(802,438,913), P3d(802,525,912), P3d(802,613,929), P3d(802,700,902), P3d(1070,0,857),P3d(1070,88,876),P3d(1070,175,874),P3d(1070,263,865),P3d(1070,350,835),P3d(1070,438,873),P3d(1070,525,835),P3d(1070,613,853),P3d(1070,700,855)] cx = [ for i in range(7)] cy = [ for i in range(9)] x_last = pts y_last = pts j = 0 k = 0 for i in range(len(pts)): x = pts[i] y = pts[i] # Load points for curves in y-direction. # This is a row of the pts "table" above. if x == x_last: # Load points cx[j].append(pts[i]) else: # Advance to next curve in y (row in pts "table". x_last = pts[i] j += 1 cx[j].append(pts[i]) # Load points for curves in x-direction. # This is a column of the pts "table" above. cy[divmod(i,9)].append(pts[i]) crvs= for i in range(6): crvs.append(rs.AddInterpCurve(cx[i])) for i in range(9): crvs.append(rs.AddInterpCurve(cy[i])) # Create surfaces from network of curves. srf = rs.AddNetworkSrf(crvs,1,0.01,0.1) # Side-to-top rs.DeleteObjects(crvs) return(srf) # Clear document rs.EnableRedraw(False) rs.DeleteObjects(rs.AllObjects()) srf = makeBase() problem(srf) rs.EnableRedraw(True)