precomputing the layout (@anvaka has built some modules for #ngraph)
using webgl ; you can try webgl for vivagraph (which wraps ngraph modules) or ngraph.pixi or ngraph.fabric or ngraph.threejs that use, as a layout, ngraph.layout, and as a rendering engine a dedicated webgl library
my graph in gexf file with 20,000 node and 590,000 edges. how i can render this gexf graph?