A rotation or movement takes about 3 seconds to react

I just started learning model, don’t know much about how to optimize the grid, I will be all merged grid directly by blender, and then loading speed is satisfactory, but there is a very headache problem, is a memory leak, continuous jump routing, if I reload the memory model will have been soaring, until the crash, I asked this question before community, It has not been solved, I do not know whether it is the model problem or the BabylonJS problem, can you help me to take a look?