Instant responsiveness in user interfaces is annoying
1. As I'm typing text into a search input, the interface wants to instantaneously pattern match my search and offer the best results. Sometimes this is helpful. In other situations, this can take my attention away by opening extraneous menus or interactive elements. To be honest, I just want to finish typing my search. Stop asking me for more input as I'm typing my input.
2. Certain websites are designed to open menus/interactive elements as the cursor hovers over particular web elements. For me, this is sometimes another distraction. Just because I moved my mouse, that doesn't mean I want to see yet another menu. The instant responsiveness can lead me to click in the wrong places due to unexpected interface components showing up. I can't tell you how many times I've chained several misclicks due to unexpected links/buttons (or lack thereof as described in 3 below).
3. Responsiveness creates expectations for feedback. Then, if some part of your application starts to lag (maybe it's the internet, maybe it's my computer), you lose the responsiveness and I get annoyed.
Am I just becoming a grumpy old guy?