When OnePlus 3 came out, one of the first issues reported by users was a touch latency. Since then, OnePlus failed to release an update that would address the issue. The same issue can be found on the OnePlus 3T as well. At first, it looked like the issue is hardware-related, but co-founder of OnePlus Carl Pei has now issued a statement saying that the issue has finally been fixed.
The fix will probably be included in the next patch/update. Carl Pei also said that they are now working on the alert slider. When can we expect the update is unknown at the moment.