Not sure what you are experiencing – CPU sluggishness, video-stage “lag”, controller lag – or exactly what part of the experience time-chain is/are giving you the problem(s).
Regarding KMS/DRM – as far as I can tell, there is an emerging driver is in development by Broadcom to enhance the performance as they, Broadcom, have a new asset in the form of an Intel former employee Eric Anholt. ETA for the driver is first half of 2015 as of today (source: article). Eric may quote something different.
Using a CRT is something that you can try using the composite out instead of HDMI while not at work. Although I have my doubts any differences will be seen.
… not to say there isn’t existing KMS work. I would suggest you focus on Raspberry Pi sources as the link you provided focuses on Windows primarily. Presumably why you asked here – but there are existing Raspberry Pi discussions on the topic (insert search engine address here).
I would open your settings on the TV itself and look for a setting named “Game Mode” I have to turn this on both of my LED HD TV’s in order to get rid of my input lag. I use this setting on all consoles hooked up to my TV, not just the Pi.
Here is an article that explains what the setting does: