I made a mesh of a hand, and it had quite a few vertices, about 20,000 (because I subdivided it multiple times). When I tried to link it to an armature, then blender ran extremely slowly, and I couldn’t make it run any faster, even by restarting the computer. Can anyone help?
No, we can’t 
I mean, armature deformations on a mesh is a heavy computation, if you have both a complex armature and a complex mesh…
Personally I keep armature and mesh on a different layer, it tends to be faster if you hide the layer you are not working on
Stefano
I’ve had some funny similar experiences with armatures, ones that for no reason run ridiculously slow when parented, despite near identical ones running fine, this could be your problem.
I had to reconstruct the armature again then parent it and voila, it worked, if I were you I’d give that a go.
If not then use subsurf instead of subdiv, Then you have the render time and run time subsurf levels. Unfortunately this means either decimating and hoping, or remaking your hand.
Armatures can deform a mesh without any weight painting or vertex grouping, but its very slow. But if you either do weight painting or vertex grouping (assigning which vertices in the mesh bend with which bone in the armature) then it should speed up dramatically. Theres loads of tutorials around for doing this.
Keith. 8)
20,000 verts, Holy Cow… I would recommend using the subdivision surfaces on a much lower poly hand if none of the other suggestions do the trick for you. You can get a decent looking hand with 100 verts and subsurfacing. Blender 2.27 Has automatic skinning-that will assign vertex groups to the nearest bone without you having to do it manually.
Good Luck!
I’m having the same problem with armatures and slow deforming meshes. Couldn’t this be a matter of getting a faster video card or a faster computer with more memory? In the mean time, I want to take S68’s advice and put the armature on a different layer. But I’m not sure how to transfer anything from one layer to the next. Is this possible and does anyone know how?
select the object you want to move, then press M, then the number of the layer you want to move to or click one of the layerbuttons that pop up when you press M.
Hans Petter
If you parent a mesh without any vertex groups to an armature, the weights get auto-calculated. That is VERY slow. Try creating a vertex group named the same as some bone on the armature and assign a few verts to it, that way autoskinning gets disabled.
Its also possible to move objects from later to layer by selecting them and then hitting F9 to display the edit buttons. You’ll notice about 1/3 of the way across the button display is a set of twenty blank squares corresponding to the 20 layers. Select whatever object/s you want to move and press the button that corresponds to the layer you want to move it to. (This method isn’t any better, its just another way to do it and as far as I know it works fine)