I just went back in to US East and took a trip around zoomed in to 149 feet. Panning takes a little time to redraw. I had over 30 apps in the multitasking bar. I deleted them and launched the app again. It does take a second or two to paint when I pan. That seems no different with more apps in the multitasking bar. If you have a corrupted app and you can't load a new one from the app store, that's nasty.

Ahhh... I just found this on the Navionics site. Looks like this is your answer. (See below). I sure hope Navionics doesn't do a total screw-up. Now that iPad, Android, and who knows what other mobile system, they'll probably be writing some ten layer deep generic code that will destroy performance on all of them. Let's hope not!

http://www.navionics.com/MobileMarineFAQs.asp?CategoryID=52&ViewCategoryID=52&MobileType=iPhoneSingle

"Q. I already have Navionics Mobile on my iPhone, why should I buy a new Navionics Mobile?
A. In time, the new apps will offer many important and innovative features that will not be available in the previous Navionics Mobile apps.
Q. I already have Navionics Mobile on my iPhone (v4.4) and it is having problems at start up? Are you going to fix this?
A. An update fixing this problem (v5.0.x) will be available shortly. It will be the last update available for the old apps. Make sure you don't miss it.
Q. I already have a Navionics Mobile app (v5.x), do you offer a discount on the new app to existing customers?
A. No, no special price will be offered to existing customers.
Q. What is the risk in keeping my original Navionics app?
A. Navionics will keep improving the new apps adding features every month. Not downloading the new app, you will not be able of benefiting from updates. You can certainly continue to enjoy the current Navionics app but it will be frozen at version 5.0.2 and not be further updated. It would be wise to make a back up copy of the app file (.ipa) that resides in your iTunes Library on your PC in case of loss or stolen property. The app will no longer be available to you on iTunes to re-download after it will have been removed from iTunes."