Viewport Performance drop once something is rendered or Material-editor is used.

[tallbox]

+1
I'm having same issues with the slate material editor. Whenever I change something, max freezes for 3-4 second. And if I have more than ten elements at once opened it takes ages to load. That is very frustrating when you are trying to keep the deadlines.

[Jpjapers]

Ive also noted the same problem with the material editor in 1.5.1 with lots of network textures.

[E_Camacho]

I've been suffering the same problem. I saw on another page to disable Windows Defender.  I instantly had better interface performance.  Not perfect, but much better.

[maru]

Similar issues should be fixed thanks to various updates in 3ds Max and Corona. There are also some speedups coming in V10.

Still, if anyone is experiencing slowdowns in the viewport, material editor, etc - please report them to us - https://support.chaos.com/hc/en-us/requests/new