On this forum, we've been known to go completely "bonkers" with an efficiency focus on a number of problems. Many trivial and funny, but some were quite large and anything but trivial.
Before anything more substantial however, we need to know the details:
1) What is the EXACT problem and all the constraints!
2) What run-time are you getting now, and with what kind of system hardware? Usually, cpu and it's system speed will do.
The hardware it's being run on is critical! For instance, my prime number problem had to run on an OLD Intel cpu @850MHz, for it's test!
Anyway, you have people here who are VERY concerned with run-time efficiency, and actually REVEL in solving problems related to it.
So, cough it up, buddy!