I just noticed my post was messed up. What I meant to say is that I get that lag with LauncherPro, so I tried the fix for this problem in terminal emulator but it caused my phone to go into a boot loop. I had to do a factory reset and I noticed the lag was on the stock launcher too.
This problem was really starting to tick me off too, mostly because I've been experiencing this since the days of the Droid 1. I had the same first mis-step as you when trying to apply the fix that used to work on my droid 1 and 3. I became determined to defeat it, and I believe I'm approaching a breakthrough. The problem, as I understand it, is some combination of a display buffer filling up (surfaceflinger, if I'm not mistaken) and the home application having the memory priority of a normal background application... so when that display buffer fills up, the space occupied by the home app is liable to be dumped. Then when you hit the home key, the application has to reload display buffer, and we're stuck waiting. I'm probably stating all this somewhat incorrectly, but I don't think I'm too far from the mark.
Anyway, the solution I found is to give the home app a higher priority so that it is further down the kill list when the display buffer starts filling up. Here's what I did:
0) You will need to be rooted to take advantage of this
1) Download
Auto Memory Manager
2) In the app, hit 'menu', go to "running processes"
3) Select "list", then hit 'menu', then "sort by name"
4) Find your home app. In my case it was "Nemus Launcher" but yours sounds like it will be "LauncherPro"
5) Tap on your launcher, and select "Always keep alive"
6) The OOM Priority number next to your launcher should decrease significantly. Lower OOM Priorities are less likely to be closed than higher ones.
That's it. One bummer is that android appears to reset these priorities as it sees fit, so you'll probably need to do this every now and then. I only did it for the first time a few days ago, and when I went in to check the priority while writing this, it had been reset. Not sure when that happened, but I'll see if I can notice a trend and update this post if I learn anything.
EDIT: Looks like I may have spoken too soon. This setting appears to get reverted back to its original value within a few minutes. I'll continue looking into it though.