Number of keyframes

Will it cause an overhead if my model has many keyframes on it?

 

not the keyframes themselves.. it is the number of fps * duration * animations * properties animated.

that is the data and all data costs runtime memory

your use case can be extreme -- 100 bones with 2,000 seconds of 30fps data? that could lead to memory bloat if not handled right but it can be compressed
http://docs.unity3d.com/Manual/FBXImporter-Animations.html
character animation IIRC use "optimal" for best results

animation authored in Unity *.anim sample rate controls data needed per second. I've found I normally only need 10 for prop animation
http://docs.unity3d.com/Manual/animeditor-UsingAnimationEditor.html
{though currently there is no information on this in the document section}

cinematics I'll to drop to 5 to save...going under 3 samples/sec can create unwanted ease-in ease-out motion

 

I have 25 bones with 4,100 keyframes.. Will it lead to memory bloat?