At first, MultiBit was all snappy. Over the course of about 4 weeks I added ~120 more receive addresses. Now, MultiBit is very sluggish, grinding the hard-drive excessively (sometimes for minutes), especially when sending payments or when exiting the program. Today, it displayed a message in the status bar that it couldn't open the wallet and that it will use some rolling backup. After that, it resynchronized for about an hour.
I worry that if things continue this way I will be faced with catastrophic data and money loss.
Do you have any hints on why this might happen or whether I could migrate to another more reliable wallet software which could import all my addresses?