@steviek Hello! You need to change the buffer size in Logic Pro and Mainstage. Set it as low as possible so that you don't get any CPU overload and reduce the latency.
If you have a powerful computer you can get away with settings like 64 or even 32. If you also reduce the sampling rate (down to something like 44.1khz) that should also help with latency as you will then be able to reduce the buffer size.