Sorry for the late reply. I've moved on from the Revo, but I spent the last year with it battling lag caused by a low free RAM condition.
The Revo has limited user-available RAM (something like 367 MB?), and users need to monitor and tend to their available RAM, which gets reduced by
- lots of apps (apps themselves, whether running or not, each take up a little RAM), and/or
- lots of widgets (widgets take up RAM), and/or
- several RAM-hungry apps that run continually.
When you experience lag, check Settings --> Applications --> Running Services. You're good if there's at least 75 - 100 MB free. Anything less and you'll experience noticeable lag. When you get down as low as 45 MB free, you'll have so much lag that it'll be difficult to answer phone calls before the caller hangs up or the call goes to voicemail.
While you're in Running Services, look at the RAM hogs. Eliminate or replace with similar but less RAM-intensive apps, if possible.
Reduce widgets to a minimum. Get rid of apps if you have a lot that you don't use (IIRC, removing 50 apps got me ~25 MB of free RAM).
On some phones, it's loaded cache that causes lag. So you might get a cache cleaner app. Though on the Revo, that was never the problem for me, as the RAM is much more limiting (although I did clean cache fairly regularly).
If you're app happy like I am, you've gotta tend the Revo. I've had the same problem with my LG Lucid 2, even with double the RAM (to 1 GB).
