Update User FAQ

User-FAQ.md

@@ -30,6 +30,10 @@ At this time, only the IC-7300 is supported. However, most Icom radios share the
 
 No. wfview is cool like that. It provides a pseudo terminal device that other programs, such as flrig and fldigi, can use to maintain control of the radio. wfview passes any commands from these other programs to the radio using a software CI-V bus. In the future, I would also like to add support for native TCP/IP control such as the XML RPC that fldigi and flrig support. 
 
+**Why is the spectrum so slow?**
+
+Unfortunately, Icom runs the spectrum data over the UART significantly slower than the USB port is capable of handling data. This results in about 10 updates per second. If it looks slow, it is. You can make the window larger to make it feel faster ;-). You can also drag the divider between the plot and the waterfall image for more flexibility. 
+
 **Can wfview's appearance be customized?**
 
 Yes. wfview has a preference file (plain text) with many adjustments, including options for a custom qt widget stylesheet and colors for various UI elements and plot elements.