Threejs：置换图和性能

Question

我在编辑完这个问题后开了一个新问题：Three.js: object light & displacementMap

我有这个戒指：

使用以下代码生成暗部：

var external = new THREE.CylinderBufferGeometry( 3.48, 3.48, 4, 800, 400, true, -1.19, 5.54 );

var materials = [];

var baseMaterial = new THREE.MeshPhongMaterial({
    color: 0x222222
});

materials.push(baseMaterial);

var textureMaterial = new THREE.MeshPhongMaterial({
    map: image, //PNG with text and symbols
    transparent: true,
    opacity: 1,
    reflectivity:0.5,
    color: 0xc0c0c0,
    emissive: 0x111111,
    specular: 0xffffff,
    shininess: 34,
    displacementMap: image, //same as map
    displacementScale: 0.15,
    displacementBias: 0
}); 

materials.push(textureMaterial);

var externalObj = THREE.SceneUtils.createMultiMaterialObject(external, materials);

问题是浏览器和计算机冻结了！

我认为问题是800x400的圆柱段，它会产生一个320000“面”的网格。有没有办法优化性能，保持这种细节水平？