Russ,

I don't know how you are doing things, but a couple come to mind:

#1. Use an 18F chip. They are generally more efficient, and their A/Ds are faster.

#2. Don't use ADCIN - You can "interleave" the converter. Write the
A/D registers directly.

A. Change to a channel
B. Go off and do something for 10uSecs or so (acquisition time)
C. Start the converter
D. Go off and do something else for 15uSecs or so (conversion time)
E. Read the converter (test the ADC DONE bit).
F.Go back to step "A"

By doing things this way, your A/D conversion time is close to zero, and you have plenty time to do whatever else you need. I did 4 simultaneous channels of 60Hz RMS conversion this way. The square root routine takes a lot of time, so I had to make every uSec count. I was using an '8723 at 40Mhz, though.