You could try this...
At start of level:
1. DrawBlock all tiles
2. GrabImage the whole screen
In main loop:
1. DrawBlock grabbed image
2. DrawBlock animated tiles only
Blitz is pretty fast at drawing large images - and the fact you'd only be drawing the animated tiles every frame should give you an increased framerate (assuming not every tile is animated, of course!).
At start of level:
1. DrawBlock all tiles
2. GrabImage the whole screen
In main loop:
1. DrawBlock grabbed image
2. DrawBlock animated tiles only
Blitz is pretty fast at drawing large images - and the fact you'd only be drawing the animated tiles every frame should give you an increased framerate (assuming not every tile is animated, of course!).