1)Reduce bufer size of audio interface.
2) Use 192Khz sample rate.
All of this two solution will smoke your CPU.
Do you connect your audio interface atlist to USB 2 or higher?
What guitar plugings you use for your guitar? Maybe it coses latency?
If you use Mac try to use Audio Units plugin format. Becus it is build in to OS it have to be very low latency.