There is a faster magic system for playing Castle Falkenstein... unfortunately, it's the GURPS Castle Falkenstein rules, having also the side effect of GURPS rules for everything else.
On the other hand, one could simply decide that each spell simply required a sorcery roll to trigger, instead of the mana gathering system; if doing so, it's a small step further to use the alternate dice-based mechanics from Comme Il Faut. In fact, using the dice mechanics might be a viable option anyway, simply replacing the mana total with a number of dice rolls totalling the needed mana.
Still, slow gathering of mana is part of the CF magic mechanics - change it at your own risk as far as feel of the game and setting. Without otherwise changing anything else, just using a single mana card flip as a rate might be a workable, if drastic, solution to mechanical slowness.