Yeah it seems to freeze up at points, and get some serious lag. I checked their dev pages and a few other people have commented to them that it's a problem. I expect they're working on it.
The other issue I noticed is that pesky default spell correction. It would be nice to have a Setting that disabled spell correction within the game. The Gostak becomes a LOT harder when they keep correcting your gostak words into "real words."
Frotz can start to slow down the longer you play a game. This is primarily because the iPhone has trouble keeping up when the length of the text in the story view area becomes too big. I'll be working on improving this for the next version, but in the mean time, you can speed things up just by getting the game to clear the screen.
1. Try using "help", supported by most games, then 'Q' to quit help and return to the game. Going into the help system will clear the story area, and improve performance.
2. If the game you're playing doesn't have help, then do "save" to save your game, then "quit", restart your game, and "restore". Restarting will clear the screen, and restoring via the command prompt will not redisplay text from the previous session.
A new version has been submitted for approval and should be available soon.
* Performance improvements: Frotz no longer slows down during long sessions, and uses less memory.
* Miscellaneous bug fixes and interface improvements.
* Added help for users new to Interactive Fiction.
* Support for deleting bundled games from Story List.
* Support for transferring games with MobileFinder.