Crushed ice is the preferred ice for a Mojito so dont worry about that. I
would suggest you invest in a heavy duty electric ice crusher. They are
expensive but absolutely invalueble after all there is more that a Mojito that
uses crushed ice! Also if you're not using wooden muddlers, start. They are
more efficient than barspoons (especially since you're using cane sugar) and
hurt less. Instead of using a lime each time use fresh squeezed lime juice
(can be bought in bottles or squeezed prior to the night starting. Using the
above tips you should be able to churn out a Mojito in around 90 seconds.
Remember the 6xP rule
Proper Preparation Prevents Piss Poor Performance!