I both love and hate ElvUI. I love it because it looks nice, but I hate it as well since it costs too much memory and CPU cycles.
It also modifies too many blizzard's frames, so it taints often. I could not control these taints, and I doubt even authors of ElvUI themselves could not fix these issues as well since 8.2.
These programmers who claim memory does not affect performance are liars.
Here is a benchmark to prove that:
I decided to write my UI. Everything will be loaded as extensions or loaded on demand, just like my LFG AddOn. It should not cost more than 100 kb memory most of the time. Also, you can track memory usage/CPU usage of any feature quickly and disable any features you do not want.
This addon is still in beta phase. I publish this for my friends to test it and provide me feedback.
memory usage. Unit (kb)