It's rude to tell someone you don't like them.
Larry has a co-worker that is working slowly on a project.
Larry wants to address his co-worker's slow work.
Larry tells his co-worker strategies to be a faster worker.
Larry tells his co-worker that their slow work makes them unlikable.
Larry's co-worker will employ the strategies and become quicker.
Larry's co-worker will be sad and have doubts about themself.