What is considered as "too many" UHD status ?

> The lteenb documentation says that too many ’UHD status: L=X U=Y S=Z’ messages is an indication of high CPU load. What is considered "too many" ?> I get a pair of the UHD status messages approximately every 4 min.

If it is only every 4 minutes, it doesn't matter.
Those traces are correlated with data loss. It indicates the system was too slow to handle signal and leads to decrease in signal quality.
The trace is displayed at most every second and counters indicates how much data have been lost. Thus if counters are low (less then 10), the impact is some packet retransmission.

If counters are high, hundreds or thousands, the system won't work.

Please first take a look at config/rf_driver/1chan.cfg file as you may update configuration depending on your cell bandwidth following comments.

If that does not help, you can monitor cpu load using top -H to check if one thread is close to 100%.This would mean your CPU is too slow.