Not really. The point of Beta's is "We have something ready we think is great. Test it and tell us what you think". Sometimes bugs like the ui latency aren't easily fixed and it hasn't been out that long. I personally think they should add some kind of "kown problems" part to the download page. Apart from that the lag is annoying but not funtionally breaking the KPA. Maybe they aren't sure what the problem is, so 4.0.4 and 4.0.5 where attempts to fix the behavior, which didn't work out. Such a complex Software isn't allways easy to troubleshoot or fix.
Apart from that (coming from a android developer background) if some ui hiccup is bothering you, you are maybe not the target audience for Beta Software. I'm not trying to offend anyone, but if you expect everything to work as good as the last stable, the beta version is not for you
I don't expect everything to work as good as the last stable; what didn't work for me in the beta was the reason I went back. It's just my opinion that they'd get more productive feedback from users if there weren't so many versions floating around. I had an entire performance ruined because of no sound coming out because of a glitch in 3.something. A glitch that was intermittent, yet part of a release version, not even a beta! Each time one thing is changed, there's no telling if there will be new unintended consequences. 4.03 was stable as far as working without any sound glitches that would ruin a performance, at least in my trials. But who knows if that will be the case if I try 4.04, 4.05, 4.06 and so on? Each time something is changed, there's always the chance that a new problem will emerge. Therefore, it's to everyone's advantage to have as few versions to put through the paces as possible. Thus my point, why release a beta that has known issues, at least without a disclaimer of what the known issues not addressed are? Such as "this beta addresses these problems, but still has these known issues." Plus with so many imperfect versions and various feedback on these forums of issues, it's hard to sort out which version people are complaining about. This then results in fewer people (such as myself) willing and able to try out betas and therefore fewer users to discover any new bugs, in particular ones that are more intermittent and easily missed like the one I experienced in 3.whatever it was.