I should clarify - I am speaking about the 60Hz LCDs found ~everywhere. Unfortunately, I cannot afford one of the newer fancier >60Hz models, and so I have little experience with them.
Once of the sources of multiple-frames of latency was the scaling/resampling stage that was needed to be compatible with non-native resolutions. Some of those algorithms are very slow. A friend of mine that makes FPGAs used in some LCDs has suggested that this slowness may be because the company making the monitor is too cheap to buy parts that were fast enough. That was a few years ago, though, so maybe these newer 144Hz monitors improved the situation.
Once of the sources of multiple-frames of latency was the scaling/resampling stage that was needed to be compatible with non-native resolutions. Some of those algorithms are very slow. A friend of mine that makes FPGAs used in some LCDs has suggested that this slowness may be because the company making the monitor is too cheap to buy parts that were fast enough. That was a few years ago, though, so maybe these newer 144Hz monitors improved the situation.