Boulder Dash is very slow, because (there is not so much code on page2, but it seems at least one screen manipulation code is there) page 2 is also Video RAM, and there are delays set on BF port, after i moved the data from FE segment to F9 ,and changed BF port to 0ch, it ran with good speed.
you can try it also, if you enter the following commands in debugger window page2 top left window:
O 00B3 F9
t 8000 bfff c000
O 00B2 F9
O 00B3 FB
O 00BF 0C
