It's not particular to the HTC Evo 4G LTE -- it's been noted in other reviews for the One X/S... (ugh that I can't seem to find) it looks like it's just an indication that even with ICS, Google has a ways to go in terms of matching Apple in OS smoothness.
iOS tends to be a storage hog, Android is definitely a cpu hog (and it certainly doesn't hate having more RAM).
That said, ICS uses the newer Linux revision 3 kernel and this phone has a lot of horsepower under the hood.
It's too soon to say if this is the ongoing complaint many have had against Android, or if this is being caused by Sense 4 - or an immature kernel not using the S4 properly.
I say this because I'm seeing a lot of Sense reboots complaints in the One X thread - and also because the first firmware of the One X was rather laggy.
So - I think you're talking about the end-user experience as shipped - and I agree with you, lag is unacceptable.
The preponderance of posts from rooters and Nexus owners prove that the blog-reported issues can be overcome - either through bloatware removal, rom replacements, configuration changes, what have you.
So, it may be tangential to your point or direct to your point, not sure, but the fault isn't necessarily Android per se - it's how it's being shipped to us as end-users.
Also, I think it's more than worth noting that by now, we all know that phones seem to ship with every useless feature turned on, and that can often affect users actual results.
In any case, my point - ICS is a big generational leap - our first major revision to Android in a few years, and Sense 4 is another generational leap.
I think the lags and Sense reboots show what happens when two big leaps are made at once.
Your mission, should you choose to accept it, is to adopt EL TEvo early and wait for performance updates. Should you or any member of the Mission LTEvo Force be caught or killed, the State Department will disavow any knowledge of your actions.
Good luck, Mr. Phelps!