Comment by makeitdouble

I think it’s all nice and fine if performance has no impact (which can be the case). For instance if your client can wait 30s for a report, no big deal.

Things go down when a query that used to take 4s now takes 30s as the product has taken off, handles 10x more data, and it’s not one user but a few hundreds having their request queued.

You wont have the luxury to not re-write that part in (probably) hard to read performant code. It can be a huge enough effort to blow away your deadlines and budget and sour pretty hard the relationship if your team struggles on something they aren’t used to do at all.