A Congo running version 5.0.x code seems much slower than the same console running version 4.3.x. This is quite visible when scrolling any long list (e.g. the Channel List).
This can be caused by setting the resolution of monitor 1 above the default 1024x768. Monitor 1 runs from the motherboard's integrated graphics, sharing ram with the operating system. Monitors 2 & 3 are driven by a dedicated graphics card and should be fine with increased resolutions.
Reset the resolution of monitor 1 to 1024x768 and do any higher resolution display from the monitor 2 or 3 outputs. Or upgrade the console to at least version 5.1.0 where the graphics handling routines were optimized to help address this issue.