Sorry, but this is a duplicate. You have to decide whether Editor performance has dropped too much - version 130 should be the topic for this issue or this one.
It’s no good style to create multiple topics just to raise the priority for an issue.
Also, this topic needs to be discussed at GitHub, not at the forum. Fortunately, you also commented here: WebGLRenderer: Render transparent doublesided in two calls by mrdoob · Pull Request #21967 · mrdoob/three.js · GitHub