What previous version are you comparing with?
The DNG handling was changed from 5.x to 6.x with noticeable slowdowns.
I'm comparing with LR 6, but the exact version I had prior to 6.1.1 I did not check (perhaps simply 6.0.0?). However, few points I want to add:
- Import (with copy) I have used with LR6 enough to be certain that at least importing has slowed down significantly with 6.1.1 when comparing to my initial LR6 version
- I have used LR 6 for a short time only, with limited amount of DNG conversions; while I feel also the DNG conversion slowed down with 6.1.1, I don't have that many data points to prove it
- Before LR 6 I used LR 4 a lot; comparing 6.1.1 to that one shows that DNG conversions have slowed down a lot