Previous ones where I was using Launcher Pro were very laggy - especially when I would first unlock the phone screen. I have OS Monitor installed and it would show high CPU usage for the launcher (Launcher Pro).
I was using the stock launcher for this .4 ROM and it was running very smoothly. The only reason that I have reverted back to a NON-ROOTED 2.1 (via 2.0.1 and an OTA upgrade) was that I had to call Verizon and get them to send me a replacement phone because I still have a green/pink spot in the middle of some of my photos (phone was already replaced once for this issue, and replacement had same problem), and my hard keyboard has been giving me double presses on some keys (like the "P"). I wanted to have it non-rooted if I had to give them any numbers off the about screens.
I am leaving it this way until my replacement comes - then BB.4 will be going back on it!