Then they should have said so on the issue "We don't value performance and wont spend any resources to fix this", rather than do the dance of giving bullshit reasons for not doing it.
Anyway, resource usage matters quite a lot, if your terminal uses CPU like an AAA game running in the background you will notice fan noises, degraded performance and potentially crashes due to overheating everywhere else in the computer.
I don't care at all if this or that terminal uses a bit more RAM or is a few milliseconds faster.